drm/udl: Restore display mode on resume

Restore the display mode whne resuming from suspend. Currently, the
display remains dark.

On resume, the CRTC's mode does not change, but the 'active' flag
changes to 'true'. Taking this into account when considering a mode
switch restores the display mode.

The bug is reproducable by using Gnome with udl and observing the
adapter's suspend/resume behavior.

Actually, the whole check added in udl_simple_display_pipe_enable()
about the crtc_state->mode_changed was bogus.  We should drop the
whole check and always apply the mode change in this function.

[ tiwai -- Drop the mode_changed check entirely instead, per Daniel's
  suggestion ]

Fixes: 997d33c35618 ("drm/udl: Inline DPMS code into CRTC enable and disable functions")
Cc: <stable@vger.kernel.org>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220908095115.23396-2-tiwai@suse.de

diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
index 169110d8fc2e193b235d8b4cc2ee5c4849d49ca0..34ce5b43c5dbdffaba73c7a8e896ca41c75b39e5 100644 (file)
--- a/drivers/gpu/drm/udl/udl_modeset.c
+++ b/drivers/gpu/drm/udl/udl_modeset.c
@@ -382,9 +382,6 @@ udl_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
 
        udl_handle_damage(fb, &shadow_plane_state->data[0], 0, 0, fb->width, fb->height);
 
-       if (!crtc_state->mode_changed)
-               return;
-
        /* enable display */
        udl_crtc_write_mode_to_hw(crtc);
 }