#define WDM_SUSPENDING 8
#define WDM_RESETTING 9
#define WDM_OVERFLOW 10
-#define WDM_DRAIN_ON_OPEN 11
#define WDM_MAX 16
"nonzero urb status received: -ESHUTDOWN\n");
goto skip_error;
case -EPIPE:
- dev_dbg(&desc->intf->dev,
+ dev_err(&desc->intf->dev,
"nonzero urb status received: -EPIPE\n");
break;
default:
desc->reslength = length;
}
}
-
- /*
- * Handling devices with the WDM_DRAIN_ON_OPEN flag set:
- * If desc->resp_count is unset, then the urb was submitted
- * without a prior notification. If the device returned any
- * data, then this implies that it had messages queued without
- * notifying us. Continue reading until that queue is flushed.
- */
- if (!desc->resp_count) {
- if (!length) {
- /* do not propagate the expected -EPIPE */
- desc->rerr = 0;
- goto unlock;
- }
- dev_dbg(&desc->intf->dev, "got %d bytes without notification\n", length);
- set_bit(WDM_RESPONDING, &desc->flags);
- usb_submit_urb(desc->response, GFP_ATOMIC);
- }
-
skip_error:
set_bit(WDM_READ, &desc->flags);
wake_up(&desc->wait);
service_outstanding_interrupt(desc);
}
-unlock:
spin_unlock(&desc->iuspin);
}
dev_err(&desc->intf->dev,
"Error submitting int urb - %d\n", rv);
rv = usb_translate_errors(rv);
- } else if (test_bit(WDM_DRAIN_ON_OPEN, &desc->flags)) {
- /*
- * Some devices keep pending messages queued
- * without resending notifications. We must
- * flush the message queue before we can
- * assume a one-to-one relationship between
- * notifications and messages in the queue
- */
- dev_dbg(&desc->intf->dev, "draining queued data\n");
- set_bit(WDM_RESPONDING, &desc->flags);
- rv = usb_submit_urb(desc->response, GFP_KERNEL);
}
} else {
rv = 0;
/* --- hotplug --- */
static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
- u16 bufsize, int (*manage_power)(struct usb_interface *, int),
- bool drain_on_open)
+ u16 bufsize, int (*manage_power)(struct usb_interface *, int))
{
int rv = -ENOMEM;
struct wdm_device *desc;
desc->manage_power = manage_power;
- /*
- * "drain_on_open" enables a hack to work around a firmware
- * issue observed on network functions, in particular MBIM
- * functions.
- *
- * Quoting section 7 of the CDC-WMC r1.1 specification:
- *
- * "The firmware shall interpret GetEncapsulatedResponse as a
- * request to read response bytes. The firmware shall send
- * the next wLength bytes from the response. The firmware
- * shall allow the host to retrieve data using any number of
- * GetEncapsulatedResponse requests. The firmware shall
- * return a zero- length reply if there are no data bytes
- * available.
- *
- * The firmware shall send ResponseAvailable notifications
- * periodically, using any appropriate algorithm, to inform
- * the host that there is data available in the reply
- * buffer. The firmware is allowed to send ResponseAvailable
- * notifications even if there is no data available, but
- * this will obviously reduce overall performance."
- *
- * These requirements, although they make equally sense, are
- * often not implemented by network functions. Some firmwares
- * will queue data indefinitely, without ever resending a
- * notification. The result is that the driver and firmware
- * loses "syncronization" if the driver ever fails to respond
- * to a single notification, something which easily can happen
- * on release(). When this happens, the driver will appear to
- * never receive notifications for the most current data. Each
- * notification will only cause a single read, which returns
- * the oldest data in the firmware's queue.
- *
- * The "drain_on_open" hack resolves the situation by draining
- * data from the firmware until none is returned, without a
- * prior notification.
- *
- * This will inevitably race with the firmware, risking that
- * we read data from the device before handling the associated
- * notification. To make things worse, some of the devices
- * needing the hack do not implement the "return zero if no
- * data is available" requirement either. Instead they return
- * an error on the subsequent read in this case. This means
- * that "winning" the race can cause an unexpected EIO to
- * userspace.
- *
- * "winning" the race is more likely on resume() than on
- * open(), and the unexpected error is more harmful in the
- * middle of an open session. The hack is therefore only
- * applied on open(), and not on resume() where it logically
- * would be equally necessary. So we define open() as the only
- * driver <-> device "syncronization point". Should we happen
- * to lose a notification after open(), then syncronization
- * will be lost until release()
- *
- * The hack should not be enabled for CDC WDM devices
- * conforming to the CDC-WMC r1.1 specification. This is
- * ensured by setting drain_on_open to false in wdm_probe().
- */
- if (drain_on_open)
- set_bit(WDM_DRAIN_ON_OPEN, &desc->flags);
-
spin_lock(&wdm_device_list_lock);
list_add(&desc->device_list, &wdm_device_list);
spin_unlock(&wdm_device_list_lock);
goto err;
ep = &iface->endpoint[0].desc;
- rv = wdm_create(intf, ep, maxcom, &wdm_manage_power, false);
+ rv = wdm_create(intf, ep, maxcom, &wdm_manage_power);
err:
return rv;
{
int rv = -EINVAL;
- rv = wdm_create(intf, ep, bufsize, manage_power, true);
+ rv = wdm_create(intf, ep, bufsize, manage_power);
if (rv < 0)
goto err;
git.samba.org / sfrench / cifs-2.6.git / commitdiff