[Intel-gfx] [PATCH 1/2] drm/i915: gen 9 can check for unclaimed registers too

[Paulo Zanoni]

Dear git bisect user,

Even though this is the patch that introduced the WARN() you're
bisecting, please notice that it's very likely that the problem you're
facing was already present before this commit. In other words: this
commit adds code to detect errors and give WARN()s about them, but the
errors were already there.

In order to continue your debug, please use the i915.mmio_debug
option, check the backtraces and try to discover which read or write
operation is causing the error message. Then check if this is
happening because the register does not exist or because its power
well is down when the operation is being done.

On my SKL machine, if I use i915.mmio_debug=999, this patch triggers
42 WARNs just by booting. I didn't investigate them yet. Normal users
are only going to get a single WARN due to the default i915.mmio_debug
setting.

Thank you for your comprehension,
Paulo

Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c     | 3 +++
 drivers/gpu/drm/i915/intel_uncore.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 1d88745..6e03e11 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -362,6 +362,7 @@ static const struct intel_device_info intel_skylake_info = {
 	.ring_mask = RENDER_RING | BSD_RING | BLT_RING | VEBOX_RING,
 	.has_llc = 1,
 	.has_ddi = 1,
+	.has_fpga_dbg = 1,
 	.has_fbc = 1,
 	GEN_DEFAULT_PIPEOFFSETS,
 	IVB_CURSOR_OFFSETS,
@@ -374,6 +375,7 @@ static const struct intel_device_info intel_skylake_gt3_info = {
 	.ring_mask = RENDER_RING | BSD_RING | BLT_RING | VEBOX_RING | BSD2_RING,
 	.has_llc = 1,
 	.has_ddi = 1,
+	.has_fpga_dbg = 1,
 	.has_fbc = 1,
 	GEN_DEFAULT_PIPEOFFSETS,
 	IVB_CURSOR_OFFSETS,
@@ -386,6 +388,7 @@ static const struct intel_device_info intel_broxton_info = {
 	.ring_mask = RENDER_RING | BSD_RING | BLT_RING | VEBOX_RING,
 	.num_pipes = 3,
 	.has_ddi = 1,
+	.has_fpga_dbg = 1,
 	.has_fbc = 1,
 	GEN_DEFAULT_PIPEOFFSETS,
 	IVB_CURSOR_OFFSETS,
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 9d3c2e4..3fa1b89 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -770,6 +770,7 @@ static u##x \
 gen9_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
 	enum forcewake_domains fw_engine; \
 	GEN6_READ_HEADER(x); \
+	hsw_unclaimed_reg_debug(dev_priv, reg, true, true); \
 	if (!SKL_NEEDS_FORCE_WAKE((dev_priv), (reg)))	\
 		fw_engine = 0; \
 	else if (FORCEWAKE_GEN9_RENDER_RANGE_OFFSET(reg))	\
@@ -783,6 +784,7 @@ gen9_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
 	if (fw_engine) \
 		__force_wake_get(dev_priv, fw_engine); \
 	val = __raw_i915_read##x(dev_priv, reg); \
+	hsw_unclaimed_reg_debug(dev_priv, reg, true, false); \
 	GEN6_READ_FOOTER; \
 }
 
@@ -983,6 +985,7 @@ gen9_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, \
 		bool trace) { \
 	enum forcewake_domains fw_engine; \
 	GEN6_WRITE_HEADER; \
+	hsw_unclaimed_reg_debug(dev_priv, reg, false, true); \
 	if (!SKL_NEEDS_FORCE_WAKE((dev_priv), (reg)) ||	\
 	    is_gen9_shadowed(dev_priv, reg)) \
 		fw_engine = 0; \
@@ -997,6 +1000,8 @@ gen9_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, \
 	if (fw_engine) \
 		__force_wake_get(dev_priv, fw_engine); \
 	__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; \
 }
 
-- 
2.5.0