This is a note to let you know that I've just added the patch titled
drm/i915: fix inconsistent brightness after resume
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-fix-inconsistent-brightness-after-resume.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 13f3fbe827d09e3182023c8c54058cbf97aa146e Mon Sep 17 00:00:00 2001
From: Jeremiah Mahler <jmmahler@xxxxxxxxx>
Date: Mon, 12 Jan 2015 11:01:03 -0800
Subject: drm/i915: fix inconsistent brightness after resume
From: Jeremiah Mahler <jmmahler@xxxxxxxxx>
commit 13f3fbe827d09e3182023c8c54058cbf97aa146e upstream.
commit 6dda730e55f412a6dfb181cae6784822ba463847
Author: Jani Nikula <jani.nikula@xxxxxxxxx>
Date: Tue Jun 24 18:27:40 2014 +0300
drm/i915: respect the VBT minimum backlight brightness
introduced a bug which resulted in inconsistent brightness levels on
different machines. If a suspended was entered with the screen off some
machines would resume with the screen at minimum brightness and others
at maximum brightness.
The following commands can be used to produce this behavior.
xset dpms force off
sleep 1
sudo systemctl suspend
(resume ...)
The root cause of this problem is a comparison which checks to see if
the backlight level is zero when the panel is enabled. If it is zero,
it is set to the maximum level. Unfortunately, not all machines have a
minimum level of zero. On those machines the level is left at the
minimum instead of begin set to the maximum.
Fix the bug by updating the comparison to check for the minimum
backlight level instead of zero. Also, expand the comparison for
the possible case when the level is less than the minimum.
Fixes: 6dda730e55f4 ("respect the VBT minimum backlight brightness")
Signed-off-by: Jeremiah Mahler <jmmahler@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_panel.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -947,7 +947,7 @@ void intel_panel_enable_backlight(struct
WARN_ON(panel->backlight.max == 0);
- if (panel->backlight.level == 0) {
+ if (panel->backlight.level <= panel->backlight.min) {
panel->backlight.level = panel->backlight.max;
if (panel->backlight.device)
panel->backlight.device->props.brightness =
Patches currently in stable-queue which might be from jmmahler@xxxxxxxxx are
queue-3.18/drm-i915-fix-inconsistent-brightness-after-resume.patch
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