[Intel-gfx] [PATCH] drm/i915: Reduce frequency of unspecific HSW reg debugging

[Chris Wilson]

Delay the expensive read on the FPGA_DBG register from once per mmio to
once per forcewake section when we are doing the general wellbeing
check rather than the targetted error detection. This almost reduces
the overhead of the debug facility (for example when submitting execlists)
to zero whilst keeping the debug checks around.

v2: Enable one-shot mmio debugging from the interrupt check as well as a
    safeguard to catch invalid display writes from outside the powerwell.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/intel_uncore.c | 56 ++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 9d3c2e420d2b..05c50cc87d1d 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -149,6 +149,30 @@ fw_domains_put(struct drm_i915_private *dev_priv, enum forcewake_domains fw_doma
 }
 
 static void
+hsw_unclaimed_reg_detect(struct drm_i915_private *dev_priv)
+{
+	static bool mmio_debug_once = true;
+
+	if (i915.mmio_debug || !mmio_debug_once)
+		return;
+
+	if (__raw_i915_read32(dev_priv, FPGA_DBG) & FPGA_DBG_RM_NOCLAIM) {
+		DRM_DEBUG("Unclaimed register detected, "
+			  "enabling oneshot unclaimed register reporting. "
+			  "Please use i915.mmio_debug=N for more information.\n");
+		__raw_i915_write32(dev_priv, FPGA_DBG, FPGA_DBG_RM_NOCLAIM);
+		i915.mmio_debug = mmio_debug_once--;
+	}
+}
+
+static void
+fw_domains_put_debug(struct drm_i915_private *dev_priv, enum forcewake_domains fw_domains)
+{
+	hsw_unclaimed_reg_detect(dev_priv);
+	fw_domains_put(dev_priv, fw_domains);
+}
+
+static void
 fw_domains_posting_read(struct drm_i915_private *dev_priv)
 {
 	struct intel_uncore_forcewake_domain *d;
@@ -623,23 +647,6 @@ hsw_unclaimed_reg_debug(struct drm_i915_private *dev_priv, u32 reg, bool read,
 	}
 }
 
-static void
-hsw_unclaimed_reg_detect(struct drm_i915_private *dev_priv)
-{
-	static bool mmio_debug_once = true;
-
-	if (i915.mmio_debug || !mmio_debug_once)
-		return;
-
-	if (__raw_i915_read32(dev_priv, FPGA_DBG) & FPGA_DBG_RM_NOCLAIM) {
-		DRM_DEBUG("Unclaimed register detected, "
-			  "enabling oneshot unclaimed register reporting. "
-			  "Please use i915.mmio_debug=N for more information.\n");
-		__raw_i915_write32(dev_priv, FPGA_DBG, FPGA_DBG_RM_NOCLAIM);
-		i915.mmio_debug = mmio_debug_once--;
-	}
-}
-
 #define GEN2_READ_HEADER(x) \
 	u##x val = 0; \
 	assert_device_not_suspended(dev_priv);
@@ -891,7 +898,6 @@ hsw_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, bool trace)
 		gen6_gt_check_fifodbg(dev_priv); \
 	} \
 	hsw_unclaimed_reg_debug(dev_priv, reg, false, false); \
-	hsw_unclaimed_reg_detect(dev_priv); \
 	GEN6_WRITE_FOOTER; \
 }
 
@@ -933,7 +939,6 @@ gen8_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, bool trace
 		__force_wake_get(dev_priv, FORCEWAKE_RENDER); \
 	__raw_i915_write##x(dev_priv, reg, val); \
 	hsw_unclaimed_reg_debug(dev_priv, reg, false, false); \
-	hsw_unclaimed_reg_detect(dev_priv); \
 	GEN6_WRITE_FOOTER; \
 }
 
@@ -1182,6 +1187,10 @@ static void intel_uncore_fw_domains_init(struct drm_device *dev)
 			       FORCEWAKE, FORCEWAKE_ACK);
 	}
 
+	if (HAS_FPGA_DBG_UNCLAIMED(dev) &&
+	    dev_priv->uncore.funcs.force_wake_put == fw_domains_put)
+		dev_priv->uncore.funcs.force_wake_put = fw_domains_put_debug;
+
 	/* All future platforms are expected to require complex power gating */
 	WARN_ON(dev_priv->uncore.fw_domains == 0);
 }
@@ -1545,11 +1554,6 @@ bool intel_has_gpu_reset(struct drm_device *dev)
 
 void intel_uncore_check_errors(struct drm_device *dev)
 {
-	struct drm_i915_private *dev_priv = dev->dev_private;
-
-	if (HAS_FPGA_DBG_UNCLAIMED(dev) &&
-	    (__raw_i915_read32(dev_priv, FPGA_DBG) & FPGA_DBG_RM_NOCLAIM)) {
-		DRM_ERROR("Unclaimed register before interrupt\n");
-		__raw_i915_write32(dev_priv, FPGA_DBG, FPGA_DBG_RM_NOCLAIM);
-	}
+	if (HAS_FPGA_DBG_UNCLAIMED(dev))
+		hsw_unclaimed_reg_detect(to_i915(dev));
 }
-- 
2.5.0