diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2012-03-22 15:00:50 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-04-13 08:33:47 -0700 |
| commit | b1db3350081817e91ab5502ca4e8915e4c32d38b (patch) | |
| tree | ccb67f6499f5d869dc5606610dcf4c039aec84a9 | |
| parent | abbea1a868f24cb748b7335ac41ba0145d168ff9 (diff) | |
drm/i915: Sanitize BIOS debugging bits from PIPECONF
commit f47166d2b0001fcb752b40c5a2d4db986dfbea68 upstream.
Quoting the BSpec from time immemorial:
PIPEACONF, bits 28:27: Frame Start Delay (Debug)
Used to delay the frame start signal that is sent to the display planes.
Care must be taken to insure that there are enough lines during VBLANK
to support this setting.
An instance of the BIOS leaving these bits set was found in the wild,
where it caused our modesetting to go all squiffy and skewiff.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=47271
Reported-and-tested-by: Eva Wang <evawang@linpus.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43012
Reported-and-tested-by: Carl Richell <carl@system76.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/gpu/drm/i915/i915_reg.h | 1 | ||||
| -rw-r--r-- | 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 1608d2a44935..2f99fd4cd715 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -2312,6 +2312,7 @@ #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 9ec9755c16ee..9011f48d3cb1 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -7278,6 +7278,12 @@ 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; |