From 6d6e732835db92e66c28dbcf258a7e3d3c71420d Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Thu, 8 Sep 2022 11:51:04 +0200
Subject: [PATCH] drm/udl: Restore display mode on resume
Git-commit: 6d6e732835db92e66c28dbcf258a7e3d3c71420d
Patch-mainline: v6.1-rc1
References: bsc#1195917

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

---
 drivers/gpu/drm/udl/udl_modeset.c |    3 ---
 1 file changed, 3 deletions(-)

--- a/drivers/gpu/drm/udl/udl_modeset.c
+++ b/drivers/gpu/drm/udl/udl_modeset.c
@@ -381,9 +381,6 @@
 
 	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);
 }