drm/i915/dg2: Introduce Wa_18017747507

WA 18017747507 applies to all DG2 skus.

BSpec: 56035, 46121, 68173
Signed-off-by: Wayne Boyer <wayne.boyer@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221031131509.3411195-1-wayne.boyer@intel.com

drivers/gpu/drm/i915/gt/intel_gt_regs.h

@@ -498,6 +498,9 @@
 #define VF_PREEMPTION				_MMIO(0x83a4)
 #define   PREEMPTION_VERTEX_COUNT		REG_GENMASK(15, 0)
 
+#define VFG_PREEMPTION_CHICKEN			_MMIO(0x83b4)
+#define   POLYGON_TRIFAN_LINELOOP_DISABLE	REG_BIT(4)
+
 #define GEN8_RC6_CTX_INFO			_MMIO(0x8504)
 
 #define XEHP_SQCM				MCR_REG(0x8724)

drivers/gpu/drm/i915/gt/intel_workarounds.c

@@ -2975,6 +2975,9 @@ general_render_compute_wa_init(struct intel_engine_cs *engine, struct i915_wa_li
 		 * Wa_22015475538:dg2
 		 */
 		wa_mcr_write_or(wal, LSC_CHICKEN_BIT_0_UDW, DIS_CHAIN_2XSIMD8);
+
+		/* Wa_18017747507:dg2 */
+		wa_masked_en(wal, VFG_PREEMPTION_CHICKEN, POLYGON_TRIFAN_LINELOOP_DISABLE);
 	}
 }