linux-kernel - [PATCH v3 01/12] drm/udl: Restore display mode on resume

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Message-Id: <20220908095115.23396-2-tiwai@suse.de>
Date:   Thu,  8 Sep 2022 11:51:04 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     Daniel Vetter <daniel.vetter@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 01/12] 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@...r.kernel.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
Suggested-by: Daniel Vetter <daniel.vetter@...ll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 drivers/gpu/drm/udl/udl_modeset.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
index 169110d8fc2e..34ce5b43c5db 100644
--- 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);
 }
-- 
2.35.3