From 406478dc911e16677fbd9c84d1d50cdffbc031ab Mon Sep 17 00:00:00 2001 From: Eric Anholt <eric@anholt.net> Date: Mon, 7 Nov 2011 16:07:04 -0800 Subject: [PATCH] drm/i915: Turn on a required 3D clock gating bit on Sandybridge. Fixes rendering failures in Unigine Tropics and Sanctuary and the mesa "fire" demo. Signed-off-by: Eric Anholt <eric@anholt.net> Cc: stable@kernel.org Signed-off-by: Keith Packard <keithp@keithp.com> --- drivers/gpu/drm/i915/i915_reg.h | 3 +++ drivers/gpu/drm/i915/intel_display.c | 9 +++++++++ 2 files changed, 12 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 5a09416e611f..b807275ea739 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -3444,6 +3444,9 @@ #define GT_FIFO_FREE_ENTRIES 0x120008 #define GT_FIFO_NUM_RESERVED_ENTRIES 20 +#define GEN6_UCGCTL2 0x9404 +# define GEN6_RCPBUNIT_CLOCK_GATE_DISABLE (1 << 12) + #define GEN6_RPNSWREQ 0xA008 #define GEN6_TURBO_DISABLE (1<<31) #define GEN6_FREQUENCY(x) ((x)<<25) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 9fa342e89454..2b2a7645cd0c 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -8148,6 +8148,15 @@ static void gen6_init_clock_gating(struct drm_device *dev) I915_WRITE(WM2_LP_ILK, 0); I915_WRITE(WM1_LP_ILK, 0); + /* According to the BSpec vol1g, bit 12 (RCPBUNIT) clock + * gating disable must be set. Failure to set it results in + * flickering pixels due to Z write ordering failures after + * some amount of runtime in the Mesa "fire" demo, and Unigine + * Sanctuary and Tropics, and apparently anything else with + * alpha test or pixel discard. + */ + I915_WRITE(GEN6_UCGCTL2, GEN6_RCPBUNIT_CLOCK_GATE_DISABLE); + /* * According to the spec the following bits should be * set in order to enable memory self-refresh and fbc: -- GitLab