[PATCH 6/9] drm/i915: Verify address field of PCBR register.

[Rodrigo Vivi <rodrigo.vivi@gmail.com>]

From: Deepak S <deepak.s@intel.com>

RC6 should be enabled only if the PCBR register is programmed properly
either BIOS or Gfx. This patches address the case where PCBR
allocation fails due buggy BIOS or due to stolen memory allocation
failed.

v2: Add #define for magic numbers (Daniel)

v3: Use VLV_PCBR_ADDR_SHIFT instead of MASK (Jani)

Signed-off-by: Deepak S <deepak.s@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
---
 drivers/gpu/drm/i915/i915_reg.h | 1 +
 drivers/gpu/drm/i915/intel_pm.c | 9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index cc3ea04..41905ab 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4987,6 +4987,7 @@
 #define GEN6_GT_GFX_RC6				0x138108
 #define GEN6_GT_GFX_RC6p			0x13810C
 #define GEN6_GT_GFX_RC6pp			0x138110
+#define VLV_PCBR_ADDR_SHIFT			12
 
 #define GEN6_PCODE_MAILBOX			0x138124
 #define   GEN6_PCODE_READY			(1<<31)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index f74d7f5..8caffb3 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3602,7 +3602,7 @@ static void valleyview_enable_rps(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_ring_buffer *ring;
-	u32 gtfifodbg, val, hw_max, hw_min, rc6_mode = 0;
+	u32 gtfifodbg, val, hw_max, hw_min, rc6_mode = 0, pcbr;
 	int i;
 
 	WARN_ON(!mutex_is_locked(&dev_priv->rps.hw_lock));
@@ -3647,7 +3647,12 @@ static void valleyview_enable_rps(struct drm_device *dev)
 		   _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH |
 				      VLV_MEDIA_RC6_COUNT_EN |
 				      VLV_RENDER_RC6_COUNT_EN));
-	if (intel_enable_rc6(dev) & INTEL_RC6_ENABLE)
+
+	/* Enable RC6 Only if the PCBR address is configured either by
+	 * BIOS or Gfx Driver */
+	pcbr = I915_READ(VLV_PCBR);
+	if (intel_enable_rc6(dev) & INTEL_RC6_ENABLE &&
+						(pcbr >> VLV_PCBR_ADDR_SHIFT))
 		rc6_mode = GEN7_RC_CTL_TO_MODE | VLV_RC_CTL_CTX_RST_PARALLEL;
 
 	intel_print_rc6_info(dev, rc6_mode);
-- 
1.8.3.1