drm: Fix docbook warnings in hdr metadata helper structures

[sfrench/cifs-2.6.git] / include / drm / drm_connector.h

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#ifndef __DRM_CONNECTOR_H__
#define __DRM_CONNECTOR_H__

#include <linux/list.h>
#include <linux/llist.h>
#include <linux/ctype.h>
#include <linux/hdmi.h>
#include <drm/drm_mode_object.h>
#include <drm/drm_util.h>

#include <uapi/drm/drm_mode.h>

struct drm_connector_helper_funcs;
struct drm_modeset_acquire_ctx;
struct drm_device;
struct drm_crtc;
struct drm_encoder;
struct drm_property;
struct drm_property_blob;
struct drm_printer;
struct edid;

enum drm_connector_force {
        DRM_FORCE_UNSPECIFIED,
        DRM_FORCE_OFF,
        DRM_FORCE_ON,         /* force on analog part normally */
        DRM_FORCE_ON_DIGITAL, /* for DVI-I use digital connector */
};

/**
 * enum drm_connector_status - status for a &drm_connector
 *
 * This enum is used to track the connector status. There are no separate
 * #defines for the uapi!
 */
enum drm_connector_status {
        /**
         * @connector_status_connected: The connector is definitely connected to
         * a sink device, and can be enabled.
         */
        connector_status_connected = 1,
        /**
         * @connector_status_disconnected: The connector isn't connected to a
         * sink device which can be autodetect. For digital outputs like DP or
         * HDMI (which can be realiable probed) this means there's really
         * nothing there. It is driver-dependent whether a connector with this
         * status can be lit up or not.
         */
        connector_status_disconnected = 2,
        /**
         * @connector_status_unknown: The connector's status could not be
         * reliably detected. This happens when probing would either cause
         * flicker (like load-detection when the connector is in use), or when a
         * hardware resource isn't available (like when load-detection needs a
         * free CRTC). It should be possible to light up the connector with one
         * of the listed fallback modes. For default configuration userspace
         * should only try to light up connectors with unknown status when
         * there's not connector with @connector_status_connected.
         */
        connector_status_unknown = 3,
};

/**
 * enum drm_connector_registration_status - userspace registration status for
 * a &drm_connector
 *
 * This enum is used to track the status of initializing a connector and
 * registering it with userspace, so that DRM can prevent bogus modesets on
 * connectors that no longer exist.
 */
enum drm_connector_registration_state {
        /**
         * @DRM_CONNECTOR_INITIALIZING: The connector has just been created,
         * but has yet to be exposed to userspace. There should be no
         * additional restrictions to how the state of this connector may be
         * modified.
         */
        DRM_CONNECTOR_INITIALIZING = 0,

        /**
         * @DRM_CONNECTOR_REGISTERED: The connector has been fully initialized
         * and registered with sysfs, as such it has been exposed to
         * userspace. There should be no additional restrictions to how the
         * state of this connector may be modified.
         */
        DRM_CONNECTOR_REGISTERED = 1,

        /**
         * @DRM_CONNECTOR_UNREGISTERED: The connector has either been exposed
         * to userspace and has since been unregistered and removed from
         * userspace, or the connector was unregistered before it had a chance
         * to be exposed to userspace (e.g. still in the
         * @DRM_CONNECTOR_INITIALIZING state). When a connector is
         * unregistered, there are additional restrictions to how its state
         * may be modified:
         *
         * - An unregistered connector may only have its DPMS changed from
         *   On->Off. Once DPMS is changed to Off, it may not be switched back
         *   to On.
         * - Modesets are not allowed on unregistered connectors, unless they
         *   would result in disabling its assigned CRTCs. This means
         *   disabling a CRTC on an unregistered connector is OK, but enabling
         *   one is not.
         * - Removing a CRTC from an unregistered connector is OK, but new
         *   CRTCs may never be assigned to an unregistered connector.
         */
        DRM_CONNECTOR_UNREGISTERED = 2,
};

enum subpixel_order {
        SubPixelUnknown = 0,
        SubPixelHorizontalRGB,
        SubPixelHorizontalBGR,
        SubPixelVerticalRGB,
        SubPixelVerticalBGR,
        SubPixelNone,

};

/**
 * struct drm_scrambling: sink's scrambling support.
 */
struct drm_scrambling {
        /**
         * @supported: scrambling supported for rates > 340 Mhz.
         */
        bool supported;
        /**
         * @low_rates: scrambling supported for rates <= 340 Mhz.
         */
        bool low_rates;
};

/*
 * struct drm_scdc - Information about scdc capabilities of a HDMI 2.0 sink
 *
 * Provides SCDC register support and capabilities related information on a
 * HDMI 2.0 sink. In case of a HDMI 1.4 sink, all parameter must be 0.
 */
struct drm_scdc {
        /**
         * @supported: status control & data channel present.
         */
        bool supported;
        /**
         * @read_request: sink is capable of generating scdc read request.
         */
        bool read_request;
        /**
         * @scrambling: sink's scrambling capabilities
         */
        struct drm_scrambling scrambling;
};


/**
 * struct drm_hdmi_info - runtime information about the connected HDMI sink
 *
 * Describes if a given display supports advanced HDMI 2.0 features.
 * This information is available in CEA-861-F extension blocks (like HF-VSDB).
 */
struct drm_hdmi_info {
        /** @scdc: sink's scdc support and capabilities */
        struct drm_scdc scdc;

        /**
         * @y420_vdb_modes: bitmap of modes which can support ycbcr420
         * output only (not normal RGB/YCBCR444/422 outputs). There are total
         * 107 VICs defined by CEA-861-F spec, so the size is 128 bits to map
         * upto 128 VICs;
         */
        unsigned long y420_vdb_modes[BITS_TO_LONGS(128)];

        /**
         * @y420_cmdb_modes: bitmap of modes which can support ycbcr420
         * output also, along with normal HDMI outputs. There are total 107
         * VICs defined by CEA-861-F spec, so the size is 128 bits to map upto
         * 128 VICs;
         */
        unsigned long y420_cmdb_modes[BITS_TO_LONGS(128)];

        /** @y420_cmdb_map: bitmap of SVD index, to extraxt vcb modes */
        u64 y420_cmdb_map;

        /** @y420_dc_modes: bitmap of deep color support index */
        u8 y420_dc_modes;
};

/**
 * enum drm_link_status - connector's link_status property value
 *
 * This enum is used as the connector's link status property value.
 * It is set to the values defined in uapi.
 *
 * @DRM_LINK_STATUS_GOOD: DP Link is Good as a result of successful
 *                        link training
 * @DRM_LINK_STATUS_BAD: DP Link is BAD as a result of link training
 *                       failure
 */
enum drm_link_status {
        DRM_LINK_STATUS_GOOD = DRM_MODE_LINK_STATUS_GOOD,
        DRM_LINK_STATUS_BAD = DRM_MODE_LINK_STATUS_BAD,
};

/**
 * enum drm_panel_orientation - panel_orientation info for &drm_display_info
 *
 * This enum is used to track the (LCD) panel orientation. There are no
 * separate #defines for the uapi!
 *
 * @DRM_MODE_PANEL_ORIENTATION_UNKNOWN: The drm driver has not provided any
 *                                      panel orientation information (normal
 *                                      for non panels) in this case the "panel
 *                                      orientation" connector prop will not be
 *                                      attached.
 * @DRM_MODE_PANEL_ORIENTATION_NORMAL:  The top side of the panel matches the
 *                                      top side of the device's casing.
 * @DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP: The top side of the panel matches the
 *                                      bottom side of the device's casing, iow
 *                                      the panel is mounted upside-down.
 * @DRM_MODE_PANEL_ORIENTATION_LEFT_UP: The left side of the panel matches the
 *                                      top side of the device's casing.
 * @DRM_MODE_PANEL_ORIENTATION_RIGHT_UP: The right side of the panel matches the
 *                                      top side of the device's casing.
 */
enum drm_panel_orientation {
        DRM_MODE_PANEL_ORIENTATION_UNKNOWN = -1,
        DRM_MODE_PANEL_ORIENTATION_NORMAL = 0,
        DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP,
        DRM_MODE_PANEL_ORIENTATION_LEFT_UP,
        DRM_MODE_PANEL_ORIENTATION_RIGHT_UP,
};

/*
 * This is a consolidated colorimetry list supported by HDMI and
 * DP protocol standard. The respective connectors will register
 * a property with the subset of this list (supported by that
 * respective protocol). Userspace will set the colorspace through
 * a colorspace property which will be created and exposed to
 * userspace.
 */

/* For Default case, driver will set the colorspace */
#define DRM_MODE_COLORIMETRY_DEFAULT                    0
/* CEA 861 Normal Colorimetry options */
#define DRM_MODE_COLORIMETRY_NO_DATA                    0
#define DRM_MODE_COLORIMETRY_SMPTE_170M_YCC             1
#define DRM_MODE_COLORIMETRY_BT709_YCC                  2
/* CEA 861 Extended Colorimetry Options */
#define DRM_MODE_COLORIMETRY_XVYCC_601                  3
#define DRM_MODE_COLORIMETRY_XVYCC_709                  4
#define DRM_MODE_COLORIMETRY_SYCC_601                   5
#define DRM_MODE_COLORIMETRY_OPYCC_601                  6
#define DRM_MODE_COLORIMETRY_OPRGB                      7
#define DRM_MODE_COLORIMETRY_BT2020_CYCC                8
#define DRM_MODE_COLORIMETRY_BT2020_RGB                 9
#define DRM_MODE_COLORIMETRY_BT2020_YCC                 10
/* Additional Colorimetry extension added as part of CTA 861.G */
#define DRM_MODE_COLORIMETRY_DCI_P3_RGB_D65             11
#define DRM_MODE_COLORIMETRY_DCI_P3_RGB_THEATER         12

/**
 * enum drm_bus_flags - bus_flags info for &drm_display_info
 *
 * This enum defines signal polarities and clock edge information for signals on
 * a bus as bitmask flags.
 *
 * The clock edge information is conveyed by two sets of symbols,
 * DRM_BUS_FLAGS_*_DRIVE_\* and DRM_BUS_FLAGS_*_SAMPLE_\*. When this enum is
 * used to describe a bus from the point of view of the transmitter, the
 * \*_DRIVE_\* flags should be used. When used from the point of view of the
 * receiver, the \*_SAMPLE_\* flags should be used. The \*_DRIVE_\* and
 * \*_SAMPLE_\* flags alias each other, with the \*_SAMPLE_POSEDGE and
 * \*_SAMPLE_NEGEDGE flags being equal to \*_DRIVE_NEGEDGE and \*_DRIVE_POSEDGE
 * respectively. This simplifies code as signals are usually sampled on the
 * opposite edge of the driving edge. Transmitters and receivers may however
 * need to take other signal timings into account to convert between driving
 * and sample edges.
 *
 * @DRM_BUS_FLAG_DE_LOW:                The Data Enable signal is active low
 * @DRM_BUS_FLAG_DE_HIGH:               The Data Enable signal is active high
 * @DRM_BUS_FLAG_PIXDATA_POSEDGE:       Legacy value, do not use
 * @DRM_BUS_FLAG_PIXDATA_NEGEDGE:       Legacy value, do not use
 * @DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE: Data is driven on the rising edge of
 *                                      the pixel clock
 * @DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE: Data is driven on the falling edge of
 *                                      the pixel clock
 * @DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE: Data is sampled on the rising edge of
 *                                      the pixel clock
 * @DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE: Data is sampled on the falling edge of
 *                                      the pixel clock
 * @DRM_BUS_FLAG_DATA_MSB_TO_LSB:       Data is transmitted MSB to LSB on the bus
 * @DRM_BUS_FLAG_DATA_LSB_TO_MSB:       Data is transmitted LSB to MSB on the bus
 * @DRM_BUS_FLAG_SYNC_POSEDGE:          Legacy value, do not use
 * @DRM_BUS_FLAG_SYNC_NEGEDGE:          Legacy value, do not use
 * @DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE:    Sync signals are driven on the rising
 *                                      edge of the pixel clock
 * @DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE:    Sync signals are driven on the falling
 *                                      edge of the pixel clock
 * @DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE:   Sync signals are sampled on the rising
 *                                      edge of the pixel clock
 * @DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE:   Sync signals are sampled on the falling
 *                                      edge of the pixel clock
 */
enum drm_bus_flags {
        DRM_BUS_FLAG_DE_LOW = BIT(0),
        DRM_BUS_FLAG_DE_HIGH = BIT(1),
        DRM_BUS_FLAG_PIXDATA_POSEDGE = BIT(2),
        DRM_BUS_FLAG_PIXDATA_NEGEDGE = BIT(3),
        DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE = DRM_BUS_FLAG_PIXDATA_POSEDGE,
        DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
        DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
        DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE = DRM_BUS_FLAG_PIXDATA_POSEDGE,
        DRM_BUS_FLAG_DATA_MSB_TO_LSB = BIT(4),
        DRM_BUS_FLAG_DATA_LSB_TO_MSB = BIT(5),
        DRM_BUS_FLAG_SYNC_POSEDGE = BIT(6),
        DRM_BUS_FLAG_SYNC_NEGEDGE = BIT(7),
        DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE = DRM_BUS_FLAG_SYNC_POSEDGE,
        DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE = DRM_BUS_FLAG_SYNC_NEGEDGE,
        DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE = DRM_BUS_FLAG_SYNC_NEGEDGE,
        DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE = DRM_BUS_FLAG_SYNC_POSEDGE,
};

/**
 * struct drm_display_info - runtime data about the connected sink
 *
 * Describes a given display (e.g. CRT or flat panel) and its limitations. For
 * fixed display sinks like built-in panels there's not much difference between
 * this and &struct drm_connector. But for sinks with a real cable this
 * structure is meant to describe all the things at the other end of the cable.
 *
 * For sinks which provide an EDID this can be filled out by calling
 * drm_add_edid_modes().
 */
struct drm_display_info {
        /**
         * @width_mm: Physical width in mm.
         */
        unsigned int width_mm;

        /**
         * @height_mm: Physical height in mm.
         */
        unsigned int height_mm;

        /**
         * @bpc: Maximum bits per color channel. Used by HDMI and DP outputs.
         */
        unsigned int bpc;

        /**
         * @subpixel_order: Subpixel order of LCD panels.
         */
        enum subpixel_order subpixel_order;

#define DRM_COLOR_FORMAT_RGB444         (1<<0)
#define DRM_COLOR_FORMAT_YCRCB444       (1<<1)
#define DRM_COLOR_FORMAT_YCRCB422       (1<<2)
#define DRM_COLOR_FORMAT_YCRCB420       (1<<3)

        /**
         * @panel_orientation: Read only connector property for built-in panels,
         * indicating the orientation of the panel vs the device's casing.
         * drm_connector_init() sets this to DRM_MODE_PANEL_ORIENTATION_UNKNOWN.
         * When not UNKNOWN this gets used by the drm_fb_helpers to rotate the
         * fb to compensate and gets exported as prop to userspace.
         */
        int panel_orientation;

        /**
         * @color_formats: HDMI Color formats, selects between RGB and YCrCb
         * modes. Used DRM_COLOR_FORMAT\_ defines, which are _not_ the same ones
         * as used to describe the pixel format in framebuffers, and also don't
         * match the formats in @bus_formats which are shared with v4l.
         */
        u32 color_formats;

        /**
         * @bus_formats: Pixel data format on the wire, somewhat redundant with
         * @color_formats. Array of size @num_bus_formats encoded using
         * MEDIA_BUS_FMT\_ defines shared with v4l and media drivers.
         */
        const u32 *bus_formats;
        /**
         * @num_bus_formats: Size of @bus_formats array.
         */
        unsigned int num_bus_formats;

        /**
         * @bus_flags: Additional information (like pixel signal polarity) for
         * the pixel data on the bus, using &enum drm_bus_flags values
         * DRM_BUS_FLAGS\_.
         */
        u32 bus_flags;

        /**
         * @max_tmds_clock: Maximum TMDS clock rate supported by the
         * sink in kHz. 0 means undefined.
         */
        int max_tmds_clock;

        /**
         * @dvi_dual: Dual-link DVI sink?
         */
        bool dvi_dual;

        /**
         * @has_hdmi_infoframe: Does the sink support the HDMI infoframe?
         */
        bool has_hdmi_infoframe;

        /**
         * @rgb_quant_range_selectable: Does the sink support selecting
         * the RGB quantization range?
         */
        bool rgb_quant_range_selectable;

        /**
         * @edid_hdmi_dc_modes: Mask of supported hdmi deep color modes. Even
         * more stuff redundant with @bus_formats.
         */
        u8 edid_hdmi_dc_modes;

        /**
         * @cea_rev: CEA revision of the HDMI sink.
         */
        u8 cea_rev;

        /**
         * @hdmi: advance features of a HDMI sink.
         */
        struct drm_hdmi_info hdmi;

        /**
         * @non_desktop: Non desktop display (HMD).
         */
        bool non_desktop;
};

int drm_display_info_set_bus_formats(struct drm_display_info *info,
                                     const u32 *formats,
                                     unsigned int num_formats);

/**
 * struct drm_tv_connector_state - TV connector related states
 * @subconnector: selected subconnector
 * @margins: margins (all margins are expressed in pixels)
 * @margins.left: left margin
 * @margins.right: right margin
 * @margins.top: top margin
 * @margins.bottom: bottom margin
 * @mode: TV mode
 * @brightness: brightness in percent
 * @contrast: contrast in percent
 * @flicker_reduction: flicker reduction in percent
 * @overscan: overscan in percent
 * @saturation: saturation in percent
 * @hue: hue in percent
 */
struct drm_tv_connector_state {
        enum drm_mode_subconnector subconnector;
        struct {
                unsigned int left;
                unsigned int right;
                unsigned int top;
                unsigned int bottom;
        } margins;
        unsigned int mode;
        unsigned int brightness;
        unsigned int contrast;
        unsigned int flicker_reduction;
        unsigned int overscan;
        unsigned int saturation;
        unsigned int hue;
};

/**
 * struct drm_connector_state - mutable connector state
 */
struct drm_connector_state {
        /** @connector: backpointer to the connector */
        struct drm_connector *connector;

        /**
         * @crtc: CRTC to connect connector to, NULL if disabled.
         *
         * Do not change this directly, use drm_atomic_set_crtc_for_connector()
         * instead.
         */
        struct drm_crtc *crtc;

        /**
         * @best_encoder:
         *
         * Used by the atomic helpers to select the encoder, through the
         * &drm_connector_helper_funcs.atomic_best_encoder or
         * &drm_connector_helper_funcs.best_encoder callbacks.
         *
         * NOTE: Atomic drivers must fill this out (either themselves or through
         * helpers), for otherwise the GETCONNECTOR and GETENCODER IOCTLs will
         * not return correct data to userspace.
         */
        struct drm_encoder *best_encoder;

        /**
         * @link_status: Connector link_status to keep track of whether link is
         * GOOD or BAD to notify userspace if retraining is necessary.
         */
        enum drm_link_status link_status;

        /** @state: backpointer to global drm_atomic_state */
        struct drm_atomic_state *state;

        /**
         * @commit: Tracks the pending commit to prevent use-after-free conditions.
         *
         * Is only set when @crtc is NULL.
         */
        struct drm_crtc_commit *commit;

        /** @tv: TV connector state */
        struct drm_tv_connector_state tv;

        /**
         * @picture_aspect_ratio: Connector property to control the
         * HDMI infoframe aspect ratio setting.
         *
         * The %DRM_MODE_PICTURE_ASPECT_\* values much match the
         * values for &enum hdmi_picture_aspect
         */
        enum hdmi_picture_aspect picture_aspect_ratio;

        /**
         * @content_type: Connector property to control the
         * HDMI infoframe content type setting.
         * The %DRM_MODE_CONTENT_TYPE_\* values much
         * match the values.
         */
        unsigned int content_type;

        /**
         * @scaling_mode: Connector property to control the
         * upscaling, mostly used for built-in panels.
         */
        unsigned int scaling_mode;

        /**
         * @content_protection: Connector property to request content
         * protection. This is most commonly used for HDCP.
         */
        unsigned int content_protection;

        /**
         * @colorspace: State variable for Connector property to request
         * colorspace change on Sink. This is most commonly used to switch
         * to wider color gamuts like BT2020.
         */
        u32 colorspace;

        /**
         * @writeback_job: Writeback job for writeback connectors
         *
         * Holds the framebuffer and out-fence for a writeback connector. As
         * the writeback completion may be asynchronous to the normal commit
         * cycle, the writeback job lifetime is managed separately from the
         * normal atomic state by this object.
         *
         * See also: drm_writeback_queue_job() and
         * drm_writeback_signal_completion()
         */
        struct drm_writeback_job *writeback_job;

        /**
         * @max_requested_bpc: Connector property to limit the maximum bit
         * depth of the pixels.
         */
        u8 max_requested_bpc;

        /**
         * @max_bpc: Connector max_bpc based on the requested max_bpc property
         * and the connector bpc limitations obtained from edid.
         */
        u8 max_bpc;

        /**
         * @hdr_output_metadata:
         * DRM blob property for HDR output metadata
         */
        struct drm_property_blob *hdr_output_metadata;
};

/**
 * struct drm_connector_funcs - control connectors on a given device
 *
 * Each CRTC may have one or more connectors attached to it.  The functions
 * below allow the core DRM code to control connectors, enumerate available modes,
 * etc.
 */
struct drm_connector_funcs {
        /**
         * @dpms:
         *
         * Legacy entry point to set the per-connector DPMS state. Legacy DPMS
         * is exposed as a standard property on the connector, but diverted to
         * this callback in the drm core. Note that atomic drivers don't
         * implement the 4 level DPMS support on the connector any more, but
         * instead only have an on/off "ACTIVE" property on the CRTC object.
         *
         * This hook is not used by atomic drivers, remapping of the legacy DPMS
         * property is entirely handled in the DRM core.
         *
         * RETURNS:
         *
         * 0 on success or a negative error code on failure.
         */
        int (*dpms)(struct drm_connector *connector, int mode);

        /**
         * @reset:
         *
         * Reset connector hardware and software state to off. This function isn't
         * called by the core directly, only through drm_mode_config_reset().
         * It's not a helper hook only for historical reasons.
         *
         * Atomic drivers can use drm_atomic_helper_connector_reset() to reset
         * atomic state using this hook.
         */
        void (*reset)(struct drm_connector *connector);

        /**
         * @detect:
         *
         * Check to see if anything is attached to the connector. The parameter
         * force is set to false whilst polling, true when checking the
         * connector due to a user request. force can be used by the driver to
         * avoid expensive, destructive operations during automated probing.
         *
         * This callback is optional, if not implemented the connector will be
         * considered as always being attached.
         *
         * FIXME:
         *
         * Note that this hook is only called by the probe helper. It's not in
         * the helper library vtable purely for historical reasons. The only DRM
         * core entry point to probe connector state is @fill_modes.
         *
         * Note that the helper library will already hold
         * &drm_mode_config.connection_mutex. Drivers which need to grab additional
         * locks to avoid races with concurrent modeset changes need to use
         * &drm_connector_helper_funcs.detect_ctx instead.
         *
         * RETURNS:
         *
         * drm_connector_status indicating the connector's status.
         */
        enum drm_connector_status (*detect)(struct drm_connector *connector,
                                            bool force);

        /**
         * @force:
         *
         * This function is called to update internal encoder state when the
         * connector is forced to a certain state by userspace, either through
         * the sysfs interfaces or on the kernel cmdline. In that case the
         * @detect callback isn't called.
         *
         * FIXME:
         *
         * Note that this hook is only called by the probe helper. It's not in
         * the helper library vtable purely for historical reasons. The only DRM
         * core entry point to probe connector state is @fill_modes.
         */
        void (*force)(struct drm_connector *connector);

        /**
         * @fill_modes:
         *
         * Entry point for output detection and basic mode validation. The
         * driver should reprobe the output if needed (e.g. when hotplug
         * handling is unreliable), add all detected modes to &drm_connector.modes
         * and filter out any the device can't support in any configuration. It
         * also needs to filter out any modes wider or higher than the
         * parameters max_width and max_height indicate.
         *
         * The drivers must also prune any modes no longer valid from
         * &drm_connector.modes. Furthermore it must update
         * &drm_connector.status and &drm_connector.edid.  If no EDID has been
         * received for this output connector->edid must be NULL.
         *
         * Drivers using the probe helpers should use
         * drm_helper_probe_single_connector_modes() to implement this
         * function.
         *
         * RETURNS:
         *
         * The number of modes detected and filled into &drm_connector.modes.
         */
        int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, uint32_t max_height);

        /**
         * @set_property:
         *
         * This is the legacy entry point to update a property attached to the
         * connector.
         *
         * This callback is optional if the driver does not support any legacy
         * driver-private properties. For atomic drivers it is not used because
         * property handling is done entirely in the DRM core.
         *
         * RETURNS:
         *
         * 0 on success or a negative error code on failure.
         */
        int (*set_property)(struct drm_connector *connector, struct drm_property *property,
                             uint64_t val);

        /**
         * @late_register:
         *
         * This optional hook can be used to register additional userspace
         * interfaces attached to the connector, light backlight control, i2c,
         * DP aux or similar interfaces. It is called late in the driver load
         * sequence from drm_connector_register() when registering all the
         * core drm connector interfaces. Everything added from this callback
         * should be unregistered in the early_unregister callback.
         *
         * This is called while holding &drm_connector.mutex.
         *
         * Returns:
         *
         * 0 on success, or a negative error code on failure.
         */
        int (*late_register)(struct drm_connector *connector);

        /**
         * @early_unregister:
         *
         * This optional hook should be used to unregister the additional
         * userspace interfaces attached to the connector from
         * late_register(). It is called from drm_connector_unregister(),
         * early in the driver unload sequence to disable userspace access
         * before data structures are torndown.
         *
         * This is called while holding &drm_connector.mutex.
         */
        void (*early_unregister)(struct drm_connector *connector);

        /**
         * @destroy:
         *
         * Clean up connector resources. This is called at driver unload time
         * through drm_mode_config_cleanup(). It can also be called at runtime
         * when a connector is being hot-unplugged for drivers that support
         * connector hotplugging (e.g. DisplayPort MST).
         */
        void (*destroy)(struct drm_connector *connector);

        /**
         * @atomic_duplicate_state:
         *
         * Duplicate the current atomic state for this connector and return it.
         * The core and helpers guarantee that any atomic state duplicated with
         * this hook and still owned by the caller (i.e. not transferred to the
         * driver by calling &drm_mode_config_funcs.atomic_commit) will be
         * cleaned up by calling the @atomic_destroy_state hook in this
         * structure.
         *
         * This callback is mandatory for atomic drivers.
         *
         * Atomic drivers which don't subclass &struct drm_connector_state should use
         * drm_atomic_helper_connector_duplicate_state(). Drivers that subclass the
         * state structure to extend it with driver-private state should use
         * __drm_atomic_helper_connector_duplicate_state() to make sure shared state is
         * duplicated in a consistent fashion across drivers.
         *
         * It is an error to call this hook before &drm_connector.state has been
         * initialized correctly.
         *
         * NOTE:
         *
         * If the duplicate state references refcounted resources this hook must
         * acquire a reference for each of them. The driver must release these
         * references again in @atomic_destroy_state.
         *
         * RETURNS:
         *
         * Duplicated atomic state or NULL when the allocation failed.
         */
        struct drm_connector_state *(*atomic_duplicate_state)(struct drm_connector *connector);

        /**
         * @atomic_destroy_state:
         *
         * Destroy a state duplicated with @atomic_duplicate_state and release
         * or unreference all resources it references
         *
         * This callback is mandatory for atomic drivers.
         */
        void (*atomic_destroy_state)(struct drm_connector *connector,
                                     struct drm_connector_state *state);

        /**
         * @atomic_set_property:
         *
         * Decode a driver-private property value and store the decoded value
         * into the passed-in state structure. Since the atomic core decodes all
         * standardized properties (even for extensions beyond the core set of
         * properties which might not be implemented by all drivers) this
         * requires drivers to subclass the state structure.
         *
         * Such driver-private properties should really only be implemented for
         * truly hardware/vendor specific state. Instead it is preferred to
         * standardize atomic extension and decode the properties used to expose
         * such an extension in the core.
         *
         * Do not call this function directly, use
         * drm_atomic_connector_set_property() instead.
         *
         * This callback is optional if the driver does not support any
         * driver-private atomic properties.
         *
         * NOTE:
         *
         * This function is called in the state assembly phase of atomic
         * modesets, which can be aborted for any reason (including on
         * userspace's request to just check whether a configuration would be
         * possible). Drivers MUST NOT touch any persistent state (hardware or
         * software) or data structures except the passed in @state parameter.
         *
         * Also since userspace controls in which order properties are set this
         * function must not do any input validation (since the state update is
         * incomplete and hence likely inconsistent). Instead any such input
         * validation must be done in the various atomic_check callbacks.
         *
         * RETURNS:
         *
         * 0 if the property has been found, -EINVAL if the property isn't
         * implemented by the driver (which shouldn't ever happen, the core only
         * asks for properties attached to this connector). No other validation
         * is allowed by the driver. The core already checks that the property
         * value is within the range (integer, valid enum value, ...) the driver
         * set when registering the property.
         */
        int (*atomic_set_property)(struct drm_connector *connector,
                                   struct drm_connector_state *state,
                                   struct drm_property *property,
                                   uint64_t val);

        /**
         * @atomic_get_property:
         *
         * Reads out the decoded driver-private property. This is used to
         * implement the GETCONNECTOR IOCTL.
         *
         * Do not call this function directly, use
         * drm_atomic_connector_get_property() instead.
         *
         * This callback is optional if the driver does not support any
         * driver-private atomic properties.
         *
         * RETURNS:
         *
         * 0 on success, -EINVAL if the property isn't implemented by the
         * driver (which shouldn't ever happen, the core only asks for
         * properties attached to this connector).
         */
        int (*atomic_get_property)(struct drm_connector *connector,
                                   const struct drm_connector_state *state,
                                   struct drm_property *property,
                                   uint64_t *val);

        /**
         * @atomic_print_state:
         *
         * If driver subclasses &struct drm_connector_state, it should implement
         * this optional hook for printing additional driver specific state.
         *
         * Do not call this directly, use drm_atomic_connector_print_state()
         * instead.
         */
        void (*atomic_print_state)(struct drm_printer *p,
                                   const struct drm_connector_state *state);
};

/* mode specified on the command line */
struct drm_cmdline_mode {
        bool specified;
        bool refresh_specified;
        bool bpp_specified;
        int xres, yres;
        int bpp;
        int refresh;
        bool rb;
        bool interlace;
        bool cvt;
        bool margins;
        enum drm_connector_force force;
};

/**
 * struct drm_connector - central DRM connector control structure
 *
 * Each connector may be connected to one or more CRTCs, or may be clonable by
 * another connector if they can share a CRTC.  Each connector also has a specific
 * position in the broader display (referred to as a 'screen' though it could
 * span multiple monitors).
 */
struct drm_connector {
        /** @dev: parent DRM device */
        struct drm_device *dev;
        /** @kdev: kernel device for sysfs attributes */
        struct device *kdev;
        /** @attr: sysfs attributes */
        struct device_attribute *attr;

        /**
         * @head:
         *
         * List of all connectors on a @dev, linked from
         * &drm_mode_config.connector_list. Protected by
         * &drm_mode_config.connector_list_lock, but please only use
         * &drm_connector_list_iter to walk this list.
         */
        struct list_head head;

        /** @base: base KMS object */
        struct drm_mode_object base;

        /** @name: human readable name, can be overwritten by the driver */
        char *name;

        /**
         * @mutex: Lock for general connector state, but currently only protects
         * @registered. Most of the connector state is still protected by
         * &drm_mode_config.mutex.
         */
        struct mutex mutex;

        /**
         * @index: Compacted connector index, which matches the position inside
         * the mode_config.list for drivers not supporting hot-add/removing. Can
         * be used as an array index. It is invariant over the lifetime of the
         * connector.
         */
        unsigned index;

        /**
         * @connector_type:
         * one of the DRM_MODE_CONNECTOR_<foo> types from drm_mode.h
         */
        int connector_type;
        /** @connector_type_id: index into connector type enum */
        int connector_type_id;
        /**
         * @interlace_allowed:
         * Can this connector handle interlaced modes? Only used by
         * drm_helper_probe_single_connector_modes() for mode filtering.
         */
        bool interlace_allowed;
        /**
         * @doublescan_allowed:
         * Can this connector handle doublescan? Only used by
         * drm_helper_probe_single_connector_modes() for mode filtering.
         */
        bool doublescan_allowed;
        /**
         * @stereo_allowed:
         * Can this connector handle stereo modes? Only used by
         * drm_helper_probe_single_connector_modes() for mode filtering.
         */
        bool stereo_allowed;

        /**
         * @ycbcr_420_allowed : This bool indicates if this connector is
         * capable of handling YCBCR 420 output. While parsing the EDID
         * blocks it's very helpful to know if the source is capable of
         * handling YCBCR 420 outputs.
         */
        bool ycbcr_420_allowed;

        /**
         * @registration_state: Is this connector initializing, exposed
         * (registered) with userspace, or unregistered?
         *
         * Protected by @mutex.
         */
        enum drm_connector_registration_state registration_state;

        /**
         * @modes:
         * Modes available on this connector (from fill_modes() + user).
         * Protected by &drm_mode_config.mutex.
         */
        struct list_head modes;

        /**
         * @status:
         * One of the drm_connector_status enums (connected, not, or unknown).
         * Protected by &drm_mode_config.mutex.
         */
        enum drm_connector_status status;

        /**
         * @probed_modes:
         * These are modes added by probing with DDC or the BIOS, before
         * filtering is applied. Used by the probe helpers. Protected by
         * &drm_mode_config.mutex.
         */
        struct list_head probed_modes;

        /**
         * @display_info: Display information is filled from EDID information
         * when a display is detected. For non hot-pluggable displays such as
         * flat panels in embedded systems, the driver should initialize the
         * &drm_display_info.width_mm and &drm_display_info.height_mm fields
         * with the physical size of the display.
         *
         * Protected by &drm_mode_config.mutex.
         */
        struct drm_display_info display_info;

        /** @funcs: connector control functions */
        const struct drm_connector_funcs *funcs;

        /**
         * @edid_blob_ptr: DRM property containing EDID if present. Protected by
         * &drm_mode_config.mutex. This should be updated only by calling
         * drm_connector_update_edid_property().
         */
        struct drm_property_blob *edid_blob_ptr;

        /** @properties: property tracking for this connector */
        struct drm_object_properties properties;

        /**
         * @scaling_mode_property: Optional atomic property to control the
         * upscaling. See drm_connector_attach_content_protection_property().
         */
        struct drm_property *scaling_mode_property;

        /**
         * @vrr_capable_property: Optional property to help userspace
         * query hardware support for variable refresh rate on a connector.
         * connector. Drivers can add the property to a connector by
         * calling drm_connector_attach_vrr_capable_property().
         *
         * This should be updated only by calling
         * drm_connector_set_vrr_capable_property().
         */
        struct drm_property *vrr_capable_property;

        /**
         * @colorspace_property: Connector property to set the suitable
         * colorspace supported by the sink.
         */
        struct drm_property *colorspace_property;

        /**
         * @path_blob_ptr:
         *
         * DRM blob property data for the DP MST path property. This should only
         * be updated by calling drm_connector_set_path_property().
         */
        struct drm_property_blob *path_blob_ptr;

        /**
         * @max_bpc_property: Default connector property for the max bpc to be
         * driven out of the connector.
         */
        struct drm_property *max_bpc_property;

#define DRM_CONNECTOR_POLL_HPD (1 << 0)
#define DRM_CONNECTOR_POLL_CONNECT (1 << 1)
#define DRM_CONNECTOR_POLL_DISCONNECT (1 << 2)

        /**
         * @polled:
         *
         * Connector polling mode, a combination of
         *
         * DRM_CONNECTOR_POLL_HPD
         *     The connector generates hotplug events and doesn't need to be
         *     periodically polled. The CONNECT and DISCONNECT flags must not
         *     be set together with the HPD flag.
         *
         * DRM_CONNECTOR_POLL_CONNECT
         *     Periodically poll the connector for connection.
         *
         * DRM_CONNECTOR_POLL_DISCONNECT
         *     Periodically poll the connector for disconnection, without
         *     causing flickering even when the connector is in use. DACs should
         *     rarely do this without a lot of testing.
         *
         * Set to 0 for connectors that don't support connection status
         * discovery.
         */
        uint8_t polled;

        /**
         * @dpms: Current dpms state. For legacy drivers the
         * &drm_connector_funcs.dpms callback must update this. For atomic
         * drivers, this is handled by the core atomic code, and drivers must
         * only take &drm_crtc_state.active into account.
         */
        int dpms;

        /** @helper_private: mid-layer private data */
        const struct drm_connector_helper_funcs *helper_private;

        /** @cmdline_mode: mode line parsed from the kernel cmdline for this connector */
        struct drm_cmdline_mode cmdline_mode;
        /** @force: a DRM_FORCE_<foo> state for forced mode sets */
        enum drm_connector_force force;
        /** @override_edid: has the EDID been overwritten through debugfs for testing? */
        bool override_edid;

#define DRM_CONNECTOR_MAX_ENCODER 3
        /**
         * @encoder_ids: Valid encoders for this connector. Please only use
         * drm_connector_for_each_possible_encoder() to enumerate these.
         */
        uint32_t encoder_ids[DRM_CONNECTOR_MAX_ENCODER];

        /**
         * @encoder: Currently bound encoder driving this connector, if any.
         * Only really meaningful for non-atomic drivers. Atomic drivers should
         * instead look at &drm_connector_state.best_encoder, and in case they
         * need the CRTC driving this output, &drm_connector_state.crtc.
         */
        struct drm_encoder *encoder;

#define MAX_ELD_BYTES   128
        /** @eld: EDID-like data, if present */
        uint8_t eld[MAX_ELD_BYTES];
        /** @latency_present: AV delay info from ELD, if found */
        bool latency_present[2];
        /**
         * @video_latency: Video latency info from ELD, if found.
         * [0]: progressive, [1]: interlaced
         */
        int video_latency[2];
        /**
         * @audio_latency: audio latency info from ELD, if found
         * [0]: progressive, [1]: interlaced
         */
        int audio_latency[2];
        /**
         * @null_edid_counter: track sinks that give us all zeros for the EDID.
         * Needed to workaround some HW bugs where we get all 0s
         */
        int null_edid_counter;

        /** @bad_edid_counter: track sinks that give us an EDID with invalid checksum */
        unsigned bad_edid_counter;

        /**
         * @edid_corrupt: Indicates whether the last read EDID was corrupt. Used
         * in Displayport compliance testing - Displayport Link CTS Core 1.2
         * rev1.1 4.2.2.6
         */
        bool edid_corrupt;

        /** @debugfs_entry: debugfs directory for this connector */
        struct dentry *debugfs_entry;

        /**
         * @state:
         *
         * Current atomic state for this connector.
         *
         * This is protected by &drm_mode_config.connection_mutex. Note that
         * nonblocking atomic commits access the current connector state without
         * taking locks. Either by going through the &struct drm_atomic_state
         * pointers, see for_each_oldnew_connector_in_state(),
         * for_each_old_connector_in_state() and
         * for_each_new_connector_in_state(). Or through careful ordering of
         * atomic commit operations as implemented in the atomic helpers, see
         * &struct drm_crtc_commit.
         */
        struct drm_connector_state *state;

        /* DisplayID bits. FIXME: Extract into a substruct? */

        /**
         * @tile_blob_ptr:
         *
         * DRM blob property data for the tile property (used mostly by DP MST).
         * This is meant for screens which are driven through separate display
         * pipelines represented by &drm_crtc, which might not be running with
         * genlocked clocks. For tiled panels which are genlocked, like
         * dual-link LVDS or dual-link DSI, the driver should try to not expose
         * the tiling and virtualize both &drm_crtc and &drm_plane if needed.
         *
         * This should only be updated by calling
         * drm_connector_set_tile_property().
         */
        struct drm_property_blob *tile_blob_ptr;

        /** @has_tile: is this connector connected to a tiled monitor */
        bool has_tile;
        /** @tile_group: tile group for the connected monitor */
        struct drm_tile_group *tile_group;
        /** @tile_is_single_monitor: whether the tile is one monitor housing */
        bool tile_is_single_monitor;

        /** @num_h_tile: number of horizontal tiles in the tile group */
        /** @num_v_tile: number of vertical tiles in the tile group */
        uint8_t num_h_tile, num_v_tile;
        /** @tile_h_loc: horizontal location of this tile */
        /** @tile_v_loc: vertical location of this tile */
        uint8_t tile_h_loc, tile_v_loc;
        /** @tile_h_size: horizontal size of this tile. */
        /** @tile_v_size: vertical size of this tile. */
        uint16_t tile_h_size, tile_v_size;

        /**
         * @free_node:
         *
         * List used only by &drm_connector_list_iter to be able to clean up a
         * connector from any context, in conjunction with
         * &drm_mode_config.connector_free_work.
         */
        struct llist_node free_node;

        /** @hdr_sink_metadata: HDR Metadata Information read from sink */
        struct hdr_sink_metadata hdr_sink_metadata;
};

#define obj_to_connector(x) container_of(x, struct drm_connector, base)

int drm_connector_init(struct drm_device *dev,
                       struct drm_connector *connector,
                       const struct drm_connector_funcs *funcs,
                       int connector_type);
void drm_connector_attach_edid_property(struct drm_connector *connector);
int drm_connector_register(struct drm_connector *connector);
void drm_connector_unregister(struct drm_connector *connector);
int drm_connector_attach_encoder(struct drm_connector *connector,
                                      struct drm_encoder *encoder);

void drm_connector_cleanup(struct drm_connector *connector);

static inline unsigned int drm_connector_index(const struct drm_connector *connector)
{
        return connector->index;
}

static inline u32 drm_connector_mask(const struct drm_connector *connector)
{
        return 1 << connector->index;
}

/**
 * drm_connector_lookup - lookup connector object
 * @dev: DRM device
 * @file_priv: drm file to check for lease against.
 * @id: connector object id
 *
 * This function looks up the connector object specified by id
 * add takes a reference to it.
 */
static inline struct drm_connector *drm_connector_lookup(struct drm_device *dev,
                struct drm_file *file_priv,
                uint32_t id)
{
        struct drm_mode_object *mo;
        mo = drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_CONNECTOR);
        return mo ? obj_to_connector(mo) : NULL;
}

/**
 * drm_connector_get - acquire a connector reference
 * @connector: DRM connector
 *
 * This function increments the connector's refcount.
 */
static inline void drm_connector_get(struct drm_connector *connector)
{
        drm_mode_object_get(&connector->base);
}

/**
 * drm_connector_put - release a connector reference
 * @connector: DRM connector
 *
 * This function decrements the connector's reference count and frees the
 * object if the reference count drops to zero.
 */
static inline void drm_connector_put(struct drm_connector *connector)
{
        drm_mode_object_put(&connector->base);
}

/**
 * drm_connector_is_unregistered - has the connector been unregistered from
 * userspace?
 * @connector: DRM connector
 *
 * Checks whether or not @connector has been unregistered from userspace.
 *
 * Returns:
 * True if the connector was unregistered, false if the connector is
 * registered or has not yet been registered with userspace.
 */
static inline bool
drm_connector_is_unregistered(struct drm_connector *connector)
{
        return READ_ONCE(connector->registration_state) ==
                DRM_CONNECTOR_UNREGISTERED;
}

const char *drm_get_connector_status_name(enum drm_connector_status status);
const char *drm_get_subpixel_order_name(enum subpixel_order order);
const char *drm_get_dpms_name(int val);
const char *drm_get_dvi_i_subconnector_name(int val);
const char *drm_get_dvi_i_select_name(int val);
const char *drm_get_tv_subconnector_name(int val);
const char *drm_get_tv_select_name(int val);
const char *drm_get_content_protection_name(int val);

int drm_mode_create_dvi_i_properties(struct drm_device *dev);
int drm_mode_create_tv_margin_properties(struct drm_device *dev);
int drm_mode_create_tv_properties(struct drm_device *dev,
                                  unsigned int num_modes,
                                  const char * const modes[]);
void drm_connector_attach_tv_margin_properties(struct drm_connector *conn);
int drm_mode_create_scaling_mode_property(struct drm_device *dev);
int drm_connector_attach_content_type_property(struct drm_connector *dev);
int drm_connector_attach_scaling_mode_property(struct drm_connector *connector,
                                               u32 scaling_mode_mask);
int drm_connector_attach_vrr_capable_property(
                struct drm_connector *connector);
int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
int drm_mode_create_colorspace_property(struct drm_connector *connector);
int drm_mode_create_content_type_property(struct drm_device *dev);
void drm_hdmi_avi_infoframe_content_type(struct hdmi_avi_infoframe *frame,
                                         const struct drm_connector_state *conn_state);

int drm_mode_create_suggested_offset_properties(struct drm_device *dev);

int drm_connector_set_path_property(struct drm_connector *connector,
                                    const char *path);
int drm_connector_set_tile_property(struct drm_connector *connector);
int drm_connector_update_edid_property(struct drm_connector *connector,
                                       const struct edid *edid);
void drm_connector_set_link_status_property(struct drm_connector *connector,
                                            uint64_t link_status);
void drm_connector_set_vrr_capable_property(
                struct drm_connector *connector, bool capable);
int drm_connector_init_panel_orientation_property(
        struct drm_connector *connector, int width, int height);
int drm_connector_attach_max_bpc_property(struct drm_connector *connector,
                                          int min, int max);

/**
 * struct drm_tile_group - Tile group metadata
 * @refcount: reference count
 * @dev: DRM device
 * @id: tile group id exposed to userspace
 * @group_data: Sink-private data identifying this group
 *
 * @group_data corresponds to displayid vend/prod/serial for external screens
 * with an EDID.
 */
struct drm_tile_group {
        struct kref refcount;
        struct drm_device *dev;
        int id;
        u8 group_data[8];
};

struct drm_tile_group *drm_mode_create_tile_group(struct drm_device *dev,
                                                  char topology[8]);
struct drm_tile_group *drm_mode_get_tile_group(struct drm_device *dev,
                                               char topology[8]);
void drm_mode_put_tile_group(struct drm_device *dev,
                             struct drm_tile_group *tg);

/**
 * struct drm_connector_list_iter - connector_list iterator
 *
 * This iterator tracks state needed to be able to walk the connector_list
 * within struct drm_mode_config. Only use together with
 * drm_connector_list_iter_begin(), drm_connector_list_iter_end() and
 * drm_connector_list_iter_next() respectively the convenience macro
 * drm_for_each_connector_iter().
 */
struct drm_connector_list_iter {
/* private: */
        struct drm_device *dev;
        struct drm_connector *conn;
};

void drm_connector_list_iter_begin(struct drm_device *dev,
                                   struct drm_connector_list_iter *iter);
struct drm_connector *
drm_connector_list_iter_next(struct drm_connector_list_iter *iter);
void drm_connector_list_iter_end(struct drm_connector_list_iter *iter);

bool drm_connector_has_possible_encoder(struct drm_connector *connector,
                                        struct drm_encoder *encoder);

/**
 * drm_for_each_connector_iter - connector_list iterator macro
 * @connector: &struct drm_connector pointer used as cursor
 * @iter: &struct drm_connector_list_iter
 *
 * Note that @connector is only valid within the list body, if you want to use
 * @connector after calling drm_connector_list_iter_end() then you need to grab
 * your own reference first using drm_connector_get().
 */
#define drm_for_each_connector_iter(connector, iter) \
        while ((connector = drm_connector_list_iter_next(iter)))

/**
 * drm_connector_for_each_possible_encoder - iterate connector's possible encoders
 * @connector: &struct drm_connector pointer
 * @encoder: &struct drm_encoder pointer used as cursor
 * @__i: int iteration cursor, for macro-internal use
 */
#define drm_connector_for_each_possible_encoder(connector, encoder, __i) \
        for ((__i) = 0; (__i) < ARRAY_SIZE((connector)->encoder_ids) && \
                     (connector)->encoder_ids[(__i)] != 0; (__i)++) \
                for_each_if((encoder) = \
                            drm_encoder_find((connector)->dev, NULL, \
                                             (connector)->encoder_ids[(__i)])) \

#endif