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drm/i915: Implement ReadHitWriteOnlyDisable.

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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 <rafael.antognolli@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171103183027.5051-1-rafael.antognolli@intel.com
This commit is contained in:
Rafael Antognolli 2017-11-03 11:30:27 -07:00 committed by Rodrigo Vivi
parent f72b84c677
commit 0a60797a0e
2 changed files with 4 additions and 0 deletions
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1
drivers/gpu/drm/i915/i915_reg.h
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@ -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

3
drivers/gpu/drm/i915/intel_engine_cs.c
View file

@ -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));