This is a note to let you know that I've just added the patch titled
drm/i915/backlight: setup backlight pwm alternate increment on backlight enable
to the 4.8-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-backlight-setup-backlight-pwm-alternate-increment-on-backlight-enable.patch
and it can be found in the queue-4.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 915b417946030e1f365c63728875cffd8db8e880 Mon Sep 17 00:00:00 2001
From: Shawn Lee <shawn.c.lee@xxxxxxxxx>
Date: Mon, 19 Sep 2016 13:35:26 +0300
Subject: drm/i915/backlight: setup backlight pwm alternate increment on backlight enable
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From: Shawn Lee <shawn.c.lee@xxxxxxxxx>
commit 915b417946030e1f365c63728875cffd8db8e880 upstream.
Backlight enable is supposed to do a full setup of the backlight. We
were missing the PWM alternate increment bit in the south chicken
registers on lpt+ pch. This potentially caused a PWM frequency change
when the chicken register value was lost e.g. on suspend.
v2 by Jani, rebase on the patch caching alt increment
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97486
References: https://bugs.freedesktop.org/show_bug.cgi?id=67454
Cc: Cooper Chiou <cooper.chiou@xxxxxxxxx>
Cc: Wei Shun Chen <wei.shun.chang@xxxxxxxxx>
Cc: Gary C Wang <gary.c.wang@xxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Shawn Lee <shawn.c.lee@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/8265f5935bd31c039ddfc82819d26c2ca1ae9cba.1474281249.git.jani.nikula@xxxxxxxxx
(cherry picked from commit e29aff05f239f8dd24e9ee7816fd96726e20105a)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_panel.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -841,7 +841,7 @@ static void lpt_enable_backlight(struct
{
struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
struct intel_panel *panel = &connector->panel;
- u32 pch_ctl1, pch_ctl2;
+ u32 pch_ctl1, pch_ctl2, schicken;
pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
@@ -850,6 +850,22 @@ static void lpt_enable_backlight(struct
I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
}
+ if (HAS_PCH_LPT(dev_priv)) {
+ schicken = I915_READ(SOUTH_CHICKEN2);
+ if (panel->backlight.alternate_pwm_increment)
+ schicken |= LPT_PWM_GRANULARITY;
+ else
+ schicken &= ~LPT_PWM_GRANULARITY;
+ I915_WRITE(SOUTH_CHICKEN2, schicken);
+ } else {
+ schicken = I915_READ(SOUTH_CHICKEN1);
+ if (panel->backlight.alternate_pwm_increment)
+ schicken |= SPT_PWM_GRANULARITY;
+ else
+ schicken &= ~SPT_PWM_GRANULARITY;
+ I915_WRITE(SOUTH_CHICKEN1, schicken);
+ }
+
pch_ctl2 = panel->backlight.max << 16;
I915_WRITE(BLC_PWM_PCH_CTL2, pch_ctl2);
Patches currently in stable-queue which might be from shawn.c.lee@xxxxxxxxx are
queue-4.8/drm-i915-backlight-setup-backlight-pwm-alternate-increment-on-backlight-enable.patch
queue-4.8/drm-i915-backlight-setup-and-cache-pwm-alternate-increment-value.patch
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