From: Rafael Antognolli Date: Fri, 3 Nov 2017 18:30:27 +0000 (-0700) Subject: drm/i915: Implement ReadHitWriteOnlyDisable. X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0a60797a0efb;p=linux.git drm/i915: Implement ReadHitWriteOnlyDisable. The workaround for this is described as: "if RenderSurfaceState.Num_Multisamples > 1, disable RCC clock gating if RenderSurfaceState.Num_Multisamples == 1, set 0x7010[14] = 1" Further documentation in the internal bug referenced by the bspec suggest that any of the above suggestions should suffice to fix the issue. We are going with disabling RCC clock gating. Unfortunately, what we are doing doesn't match the name of the workaround, but at least it matches its description. This change improves CNL stability by avoiding some of the hangs seen in the platform. v2: Only disable RCC clock gating. Signed-off-by: Rafael Antognolli Reviewed-by: Rodrigo Vivi Signed-off-by: Rodrigo Vivi Link: https://patchwork.freedesktop.org/patch/msgid/20171103183027.5051-1-rafael.antognolli@intel.com --- diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index f0f8f60596528..6ef33422f7629 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -3837,6 +3837,7 @@ enum { */ #define SLICE_UNIT_LEVEL_CLKGATE _MMIO(0x94d4) #define SARBUNIT_CLKGATE_DIS (1 << 5) +#define RCCUNIT_CLKGATE_DIS (1 << 7) /* * Display engine regs diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c index 6997306be0d28..6cb8e3ed97e4d 100644 --- a/drivers/gpu/drm/i915/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/intel_engine_cs.c @@ -1320,6 +1320,9 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine) WA_SET_FIELD_MASKED(GEN8_CS_CHICKEN1, GEN9_PREEMPT_GPGPU_LEVEL_MASK, GEN9_PREEMPT_GPGPU_COMMAND_LEVEL); + /* ReadHitWriteOnlyDisable: cnl */ + WA_SET_BIT_MASKED(SLICE_UNIT_LEVEL_CLKGATE, RCCUNIT_CLKGATE_DIS); + /* WaEnablePreemptionGranularityControlByUMD:cnl */ I915_WRITE(GEN7_FF_SLICE_CS_CHICKEN1, _MASKED_BIT_ENABLE(GEN9_FFSC_PERCTX_PREEMPT_CTRL));