[PATCH v3 7/8] drm/i915/skl: Enable Per context Preemption granularity control

Arun Siluvery
2016-01-21T21:44:06Z

Per context preemption granularity control is only available from SKL:E0+

Actual WA is to disable percontext preemption granularity control until D0
which is the default case so this is equivalent to the inverse of
WaDisablePerCtxtPreemptionGranularityControl:skl

v2: add some detail to commit msg (Chris)

Reviewed-by: Nick Hoath <nicholas.hoath@intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 3 +++
drivers/gpu/drm/i915/intel_ringbuffer.c | 10 ++++++++++
2 files changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index c51e7e9..65e32a3 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5995,6 +5995,9 @@ enum skl_disp_power_wells {
#define SKL_DFSM_CDCLK_LIMIT_450 (2 << 23)
#define SKL_DFSM_CDCLK_LIMIT_337_5 (3 << 23)

+#define GEN7_FF_SLICE_CS_CHICKEN1 _MMIO(0x20e0)
+#define GEN9_FFSC_PERCTX_PREEMPT_CTRL (1<<14)
+
#define FF_SLICE_CS_CHICKEN2 _MMIO(0x20e4)
#define GEN9_TSG_BARRIER_ACK_DISABLE (1<<8)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index ce64519..e91fb70 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1044,6 +1044,16 @@ static int skl_init_workarounds(struct intel_engine_cs *ring)
if (ret)
return ret;

+ /*
+ * Actual WA is to disable percontext preemption granularity control
+ * until D0 which is the default case so this is equivalent to
+ * !WaDisablePerCtxtPreemptionGranularityControl:skl
+ */
+ if (IS_SKL_REVID(dev, SKL_REVID_E0, REVID_FOREVER)) {
+ I915_WRITE(GEN7_FF_SLICE_CS_CHICKEN1,
+ _MASKED_BIT_ENABLE(GEN9_FFSC_PERCTX_PREEMPT_CTRL));
+ }
+
if (IS_SKL_REVID(dev, 0, SKL_REVID_D0)) {
/* WaDisableChickenBitTSGBarrierAckForFFSliceCS:skl */
I915_WRITE(FF_SLICE_CS_CHICKEN2,