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ACK: [Oneiric SRU] drm/i915: Fix inconsistent backlight level during disabled

Message ID 4ED016A2.4000805@canonical.com
State New
Headers show

Commit Message

Tim Gardner Nov. 25, 2011, 10:28 p.m. UTC 
On 11/25/2011 03:24 PM, Kamal Mostafa wrote:
> Please consider cherry-picking this patch from torvalds/linux.git for
> Oneiric:
>
>      drm/i915: Fix inconsistent backlight level during disabled
>      04b38670cf46c096705f24e92a8747d1ab89e53c
>
> It applies cleanly, and fixes
>
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/872652
> screensaver backlight stuck off, system looks hung
>
> which affects a large number of users.  The patch is Cc:<stable>  so
> will land in Oneiric anyway, but it would be nice to get this one sooner
> rather than later.
>
>   -Kamal
>
>

Patch attached for convenient review.
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Patch

From 04b38670cf46c096705f24e92a8747d1ab89e53c Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Wed, 16 Nov 2011 10:58:03 +0100
Subject: [PATCH] drm/i915: Fix inconsistent backlight level during disabled

When the brightness property is inquired while the backlight is disabled,
the driver returns a wrong value (zero) because it probes the value after
the backlight was turned off.  This caused a black screen even after the
backlight is enabled again.  It should return the internal backlight_level
instead, so that it won't be influenced by the backlight-enable state.

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=41926
BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/872652

Tested-by: Kamal Mostafa <kamal@canonical.com>
Cc: Alex Davis <alex14641@yahoo.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Keith Packard <keithp@keithp.com>
---
 drivers/gpu/drm/i915/intel_panel.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 499d4c0..21f60b7 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -326,7 +326,8 @@  static int intel_panel_update_status(struct backlight_device *bd)
 static int intel_panel_get_brightness(struct backlight_device *bd)
 {
 	struct drm_device *dev = bl_get_data(bd);
-	return intel_panel_get_backlight(dev);
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	return dev_priv->backlight_level;
 }
 
 static const struct backlight_ops intel_panel_bl_ops = {
-- 
1.7.0.4