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Commit 6db65cbb authored by Takashi Iwai's avatar Takashi Iwai Committed by Daniel Vetter
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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: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 58bf8062

drivers/gpu/drm/i915/i915_suspend.c

+4 −1
Original line number Diff line number Diff line
@@ -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);