drm/udl: Restore display mode on resume

commit 6d6e732835db92e66c28dbcf258a7e3d3c71420d upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
index e67c40a48fb46cd2ed6d71625667861ecd03cfd5..b43e6ff06310f4ae7f4acc57ee2b7f2d5af3190d 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);
 }