[Intel-gfx] [PATCH v3] 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)

v3: Move programming to general_render_compute_wa_init() (Matt)

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 | 9 +++++++++
 2 files changed, 13 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..ea674e456cd76 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -2737,6 +2737,15 @@ general_render_compute_wa_init(struct intel_engine_cs *engine, struct i915_wa_li
 		wa_write_or(wal, VDBX_MOD_CTRL, FORCE_MISS_FTLB);
 		wa_write_or(wal, VEBX_MOD_CTRL, FORCE_MISS_FTLB);
 	}
+
+	if (IS_DG2(i915)) {
+		/* Performance tuning for Ray-tracing */
+		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));
+	}
 }
 
 static void
-- 
2.34.1