drm/i915: Fix eDP blank screen after S3 resume on HP desktops

This patch fixes the problem on some HP desktop machines with eDP
which give blank screens after S3 resume.

It turned out that BLC_PWM_CPU_CTL must be written after
BLC_PWM_CPU_CTL2.  Otherwise it doesn't take effect on these
SNB machines.

Tested with 3.5-rc3 kernel.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49233

Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Takashi Iwai 2012-06-21 15:30:41 +02:00 committed by Daniel Vetter
parent 58bf8062d0
commit 6db65cbb94

View File

@ -740,8 +740,11 @@ static void i915_restore_display(struct drm_device *dev)
if (HAS_PCH_SPLIT(dev)) {
I915_WRITE(BLC_PWM_PCH_CTL1, dev_priv->saveBLC_PWM_CTL);
I915_WRITE(BLC_PWM_PCH_CTL2, dev_priv->saveBLC_PWM_CTL2);
I915_WRITE(BLC_PWM_CPU_CTL, dev_priv->saveBLC_CPU_PWM_CTL);
/* NOTE: BLC_PWM_CPU_CTL must be written after BLC_PWM_CPU_CTL2;
* otherwise we get blank eDP screen after S3 on some machines
*/
I915_WRITE(BLC_PWM_CPU_CTL2, dev_priv->saveBLC_CPU_PWM_CTL2);
I915_WRITE(BLC_PWM_CPU_CTL, dev_priv->saveBLC_CPU_PWM_CTL);
I915_WRITE(PCH_PP_ON_DELAYS, dev_priv->savePP_ON_DELAYS);
I915_WRITE(PCH_PP_OFF_DELAYS, dev_priv->savePP_OFF_DELAYS);
I915_WRITE(PCH_PP_DIVISOR, dev_priv->savePP_DIVISOR);