[Intel-gfx] [PATCH v2] drm/i915/dg2: Add performance workaround 18019455067

[Lionel Landwerlin]

The recommended number of stackIDs for Ray Tracing subsystem is 512
rather than 2048 (default HW programming).

v2: Move the programming to dg2_ctx_gt_tuning_init() (Lucas)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_gt_regs.h     | 4 ++++
 drivers/gpu/drm/i915/gt/intel_workarounds.c | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
index 07ef111947b8c..12fc87b957425 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
@@ -1112,6 +1112,10 @@
 #define   GEN12_PUSH_CONST_DEREF_HOLD_DIS	REG_BIT(8)
 
 #define RT_CTRL					_MMIO(0xe530)
+#define   RT_CTRL_NUMBER_OF_STACKIDS_MASK	REG_GENMASK(6, 5)
+#define   NUMBER_OF_STACKIDS_512		2
+#define   NUMBER_OF_STACKIDS_1024		1
+#define   NUMBER_OF_STACKIDS_2048		0
 #define   DIS_NULL_QUERY			REG_BIT(10)
 
 #define EU_PERF_CNTL1				_MMIO(0xe558)
diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index 3213c593a55f4..4d80716b957d4 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -575,6 +575,11 @@ static void dg2_ctx_gt_tuning_init(struct intel_engine_cs *engine,
 	       FF_MODE2_TDS_TIMER_MASK,
 	       FF_MODE2_TDS_TIMER_128,
 	       0, false);
+	wa_write_clr_set(wal,
+			 RT_CTRL,
+			 RT_CTRL_NUMBER_OF_STACKIDS_MASK,
+			 REG_FIELD_PREP(RT_CTRL_NUMBER_OF_STACKIDS_MASK,
+					NUMBER_OF_STACKIDS_512));
 }
 
 /*
-- 
2.34.1