[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.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/intel_uncore.c | 47 ++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index ab5cc94588e1..6b065592aede 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;
@@ -561,23 +585,6 @@ 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);
@@ -829,7 +836,6 @@ 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; \
 }
 
@@ -871,7 +877,6 @@ 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; \
 }
 
@@ -1043,7 +1048,7 @@ static void intel_uncore_fw_domains_init(struct drm_device *dev)
 
 	if (IS_GEN9(dev)) {
 		dev_priv->uncore.funcs.force_wake_get = fw_domains_get;
-		dev_priv->uncore.funcs.force_wake_put = fw_domains_put;
+		dev_priv->uncore.funcs.force_wake_put = fw_domains_put_debug;
 		fw_domain_init(dev_priv, FW_DOMAIN_ID_RENDER,
 			       FORCEWAKE_RENDER_GEN9,
 			       FORCEWAKE_ACK_RENDER_GEN9);
@@ -1066,7 +1071,7 @@ static void intel_uncore_fw_domains_init(struct drm_device *dev)
 	} else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
 		dev_priv->uncore.funcs.force_wake_get =
 			fw_domains_get_with_thread_status;
-		dev_priv->uncore.funcs.force_wake_put = fw_domains_put;
+		dev_priv->uncore.funcs.force_wake_put = fw_domains_put_debug;
 		fw_domain_init(dev_priv, FW_DOMAIN_ID_RENDER,
 			       FORCEWAKE_MT, FORCEWAKE_ACK_HSW);
 	} else if (IS_IVYBRIDGE(dev)) {
-- 
2.1.4