| From | Greg Kroah-Hartman <> | Subject | [ 28/68] drm/i915: Fix eDP blank screen after S3 resume on HP desktops | Date | Thu, 12 Jul 2012 16:02:02 -0700 |
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From: Greg KH <gregkh@linuxfoundation.org>
3.0-stable review patch. If anyone has any objections, please let me know.
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From: Takashi Iwai <tiwai@suse.de>
commit 6db65cbb941f9d433659bdad02b307f6d94465df upstream.
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
Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/gpu/drm/i915/i915_suspend.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/i915_suspend.c +++ b/drivers/gpu/drm/i915/i915_suspend.c @@ -739,8 +739,11 @@ static void i915_restore_display(struct 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);
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