[PATCH 33/59] drm/i915: Implement WaDisableVFclkgate.

[Timo Aaltonen]

From: Rafael Antognolli <rafael.antognolli at intel.com>

BugLink: http://bugs.launchpad.net/bugs/1757573

This workaround supposedly fixes some hangs in the VF unit.

Signed-off-by: Rafael Antognolli <rafael.antognolli at intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171216001117.14232-1-rafael.antognolli@intel.com
(cherry picked from commit 01ab0f9216070f3337b3da8953a259072f5bd4f7)
Signed-off-by: Timo Aaltonen <timo.aaltonen at canonical.com>
---
 drivers/gpu/drm/i915/i915_reg.h | 3 +++
 drivers/gpu/drm/i915/intel_pm.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 44aede3f6a84..283d2adb9122 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3837,6 +3837,9 @@ enum {
 #define  SARBUNIT_CLKGATE_DIS		(1 << 5)
 #define  RCCUNIT_CLKGATE_DIS		(1 << 7)
 
+#define UNSLICE_UNIT_LEVEL_CLKGATE	_MMIO(0x9434)
+#define  VFUNIT_CLKGATE_DIS		(1 << 20)
+
 /*
  * Display engine regs
  */
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index dc42ded934ef..8e65af7ead13 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -8542,6 +8542,11 @@ static void cnl_init_clock_gating(struct drm_i915_private *dev_priv)
 	if (IS_CNL_REVID(dev_priv, CNL_REVID_A0, CNL_REVID_B0))
 		val |= SARBUNIT_CLKGATE_DIS;
 	I915_WRITE(SLICE_UNIT_LEVEL_CLKGATE, val);
+
+	/* WaDisableVFclkgate:cnl */
+	val = I915_READ(UNSLICE_UNIT_LEVEL_CLKGATE);
+	val |= VFUNIT_CLKGATE_DIS;
+	I915_WRITE(UNSLICE_UNIT_LEVEL_CLKGATE, val);
 }
 
 static void cfl_init_clock_gating(struct drm_i915_private *dev_priv)
-- 
2.15.1