drm/i915/dg2: Add Wa_14015795083

i915 must disable Render DOP clock gating globally.

v2:
- Addressed cosmetic review comments.

Bspec: 52621
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Badal Nilawar <badal.nilawar@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@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/20220607104542.8559-1-anshuman.gupta@intel.com

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

@@ -631,6 +631,7 @@
 
 #define GEN7_MISCCPCTL				_MMIO(0x9424)
 #define   GEN7_DOP_CLOCK_GATE_ENABLE		(1 << 0)
+#define   GEN12_DOP_CLOCK_GATE_RENDER_ENABLE	REG_BIT(1)
 #define   GEN8_DOP_CLOCK_GATE_CFCLK_ENABLE	(1 << 2)
 #define   GEN8_DOP_CLOCK_GATE_GUC_ENABLE	(1 << 4)
 #define   GEN8_DOP_CLOCK_GATE_MEDIA_ENABLE	(1 << 6)

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

@@ -1486,6 +1486,9 @@ dg2_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
 	 * performance guide section.
 	 */
 	wa_write_or(wal, GEN12_SQCM, EN_32B_ACCESS);
+
+	/* Wa_14015795083 */
+	wa_write_clr(wal, GEN7_MISCCPCTL, GEN12_DOP_CLOCK_GATE_RENDER_ENABLE);
 }
 
 static void