[Intel-gfx] [PATCH] drm/i915: Unclaimed register reporting for VLV

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Supposedly VLV can report when the display engine didn't claim a
register access. Try to hook it up to I915_WRITE().

Totally untested as of now.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
Found this sitting on a branch in my machine. I quickly wrote it a while
back as I was trawling the docs. I never got around to testing it. Maybe
someone else has the interest to try it out...

 drivers/gpu/drm/i915/i915_drv.c | 23 +++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_reg.h |  5 +++++
 2 files changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 624cdfc..43192a6 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1225,6 +1225,27 @@ hsw_unclaimed_reg_check(struct drm_i915_private *dev_priv, u32 reg)
 	}
 }
 
+static void
+vlv_unclaimed_reg_clear(struct drm_i915_private *dev_priv, u32 reg)
+{
+	if (IS_VALLEYVIEW(dev_priv->dev) &&
+	    I915_READ_NOTRACE(CLAIM_ER) & (CTR_OVERFLOW | CLAIM_ER_CTR)) {
+		DRM_ERROR("Unknown unclaimed register before writing to %x\n",
+			  reg);
+		I915_WRITE_NOTRACE(CLAIM_ER, CLAIM_ER_CLR);
+	}
+}
+
+static void
+vlv_unclaimed_reg_check(struct drm_i915_private *dev_priv, u32 reg)
+{
+	if (IS_VALLEYVIEW(dev_priv->dev) &&
+	    I915_READ_NOTRACE(CLAIM_ER) & (CTR_OVERFLOW | CLAIM_ER_CTR)) {
+		DRM_ERROR("Unclaimed write to %x\n", reg);
+		I915_WRITE_NOTRACE(CLAIM_ER, CLAIM_ER_CLR);
+	}
+}
+
 #define __i915_read(x, y) \
 u##x i915_read##x(struct drm_i915_private *dev_priv, u32 reg) { \
 	u##x val = 0; \
@@ -1262,11 +1283,13 @@ void i915_write##x(struct drm_i915_private *dev_priv, u32 reg, u##x val) { \
 	if (IS_GEN5(dev_priv->dev)) \
 		ilk_dummy_write(dev_priv); \
 	hsw_unclaimed_reg_clear(dev_priv, reg); \
+	vlv_unclaimed_reg_clear(dev_priv, reg); \
 	write##y(val, dev_priv->regs + reg); \
 	if (unlikely(__fifo_ret)) { \
 		gen6_gt_check_fifodbg(dev_priv); \
 	} \
 	hsw_unclaimed_reg_check(dev_priv, reg); \
+	vlv_unclaimed_reg_check(dev_priv, reg); \
 }
 __i915_write(8, b)
 __i915_write(16, w)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index dca3504..9d05675 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -651,6 +651,11 @@
 
 #define DERRMR		0x44050
 
+#define CLAIM_ER		(VLV_DISPLAY_BASE + 0x2028)
+#define   CLAIM_ER_CLR		(1 << 31)
+#define   CTR_OVERFLOW		(1 << 16)
+#define   CLAIM_ER_CTR		0xffff
+
 /* GM45+ chicken bits -- debug workaround bits that may be required
  * for various sorts of correct behavior.  The top 16 bits of each are
  * the enables for writing to the corresponding low bit.
-- 
1.8.1.5