linux-kernel - [PATCH 5.10 040/390] drm/udl: Restore display mode on resume

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Date:   Mon, 24 Oct 2022 13:27:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Daniel Vetter <daniel.vetter@...ll.ch>,
        Takashi Iwai <tiwai@...e.de>,
        Thomas Zimmermann <tzimmermann@...e.de>
Subject: [PATCH 5.10 040/390] drm/udl: Restore display mode on resume

From: Takashi Iwai <tiwai@...e.de>

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@...r.kernel.org>
Suggested-by: Daniel Vetter <daniel.vetter@...ll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220908095115.23396-2-tiwai@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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
@@ -400,9 +400,6 @@ udl_simple_display_pipe_enable(struct dr
 
 	udl_handle_damage(fb, 0, 0, fb->width, fb->height);
 
-	if (!crtc_state->mode_changed)
-		return;
-
 	/* enable display */
 	udl_crtc_write_mode_to_hw(crtc);
 }