drm/i915/icl: Wa_1406838659

Disable CGPSF unit clock gating to prevent an issue.

v2: Rebased on top of the WA refactoring
v3: Added References (Mika)
v4:
  - Rebased
  - C, not lisp (Chris)
  - Remove unintentional whitespaces (Mika)
  - Fixed in C0 (Mika)

References: HSDES#1406838659
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1525814984-20039-13-git-send-email-oscar.mateo@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -3848,6 +3848,9 @@ enum {
 #define UNSLICE_UNIT_LEVEL_CLKGATE	_MMIO(0x9434)
 #define  VFUNIT_CLKGATE_DIS		(1 << 20)
 
+#define INF_UNIT_LEVEL_CLKGATE		_MMIO(0x9560)
+#define   CGPSF_CLKGATE_DIS		(1 << 3)
+
 /*
  * Display engine regs
  */

drivers/gpu/drm/i915/intel_workarounds.c

@@ -755,6 +755,12 @@ static void icl_gt_workarounds_apply(struct drm_i915_private *dev_priv)
 	I915_WRITE(GEN10_L3_CHICKEN_MODE_REGISTER,
 		   I915_READ(GEN10_L3_CHICKEN_MODE_REGISTER) |
 		   GEN11_I2M_WRITE_DISABLE);
+
+	/* Wa_1406838659:icl (pre-prod) */
+	if (IS_ICL_REVID(dev_priv, ICL_REVID_A0, ICL_REVID_B0))
+		I915_WRITE(INF_UNIT_LEVEL_CLKGATE,
+			   I915_READ(INF_UNIT_LEVEL_CLKGATE) |
+			   CGPSF_CLKGATE_DIS);
 }
 
 void intel_gt_workarounds_apply(struct drm_i915_private *dev_priv)