System76 - Intel DRM patch
Carl Richell
carl at system76.com
Sun Apr 1 21:55:01 UTC 2012
Hi,
We'd like to make sure 12.04 is flawless on our next-gen laptops. A
kernel patch is required to fix an offset desktop bug. The patch applies
cleanly on the current precise kernel. Please see:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/968307
https://bugzilla.kernel.org/show_bug.cgi?id=43012
-- Carl
References: https://bugs.freedesktop.org/show_bug.cgi?id=47271
Signed-off-by: Chris Wilson<chris at chris-wilson.co.uk>
Cc: stable at kernel.org
---
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_display.c | 6 ++++++
2 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 3d9ba01..218b3db9 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2385,6 +2385,7 @@
#define PIPECONF_DISABLE 0
#define PIPECONF_DOUBLE_WIDE (1<<30)
#define I965_PIPECONF_ACTIVE (1<<30)
+#define PIPECONF_FRAME_START_DELAY_MASK (3<<27)
#define PIPECONF_SINGLE_WIDE 0
#define PIPECONF_PIPE_UNLOCKED 0
#define PIPECONF_PIPE_LOCKED (1<<25)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 6b0562b..73ea6e9 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7695,6 +7695,12 @@ static void intel_sanitize_modesetting(struct drm_device *dev,
struct drm_i915_private *dev_priv = dev->dev_private;
u32 reg, val;
+ /* Clear any frame start delays used for debugging left by the BIOS */
+ for_each_pipe(pipe) {
+ reg = PIPECONF(pipe);
+ I915_WRITE(reg, I915_READ(reg)& ~PIPECONF_FRAME_START_DELAY_MASK);
+ }
+
if (HAS_PCH_SPLIT(dev))
return;
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