[PATCH 1/4] drm/i915: Detect page faults during hangcheck

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

From: Chris Wilson <chris@chris-wilson.co.uk>

On Sandybridge+, the GPU provides the ERROR register for detecting page
faults. Hook this up to our hangcheck so that we can dump the error
state soon after such an event occurs. This would be better inside an
interrupt handler, but it serves a purpose here as it detects that our
initial context setup is invalid...

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_irq.c     | 5 +++++
 drivers/gpu/drm/i915/intel_uncore.c | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 49ad5fb..ea668fc 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2929,6 +2929,11 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
 	if (!i915.enable_hangcheck)
 		return;
 
+	if (INTEL_INFO(dev_priv)->gen >= 6 && I915_READ(ERROR_GEN6)) {
+		i915_handle_error(dev, false, "GPU reported a page fault");
+		I915_WRITE(ERROR_GEN6, 0);
+	}
+
 	for_each_ring(ring, dev_priv, i) {
 		u64 acthd;
 		u32 seqno;
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index ab5cc94..c58535e 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -359,6 +359,8 @@ static void __intel_uncore_early_sanitize(struct drm_device *dev,
 	if (IS_GEN6(dev) || IS_GEN7(dev))
 		__raw_i915_write32(dev_priv, GTFIFODBG,
 				   __raw_i915_read32(dev_priv, GTFIFODBG));
+	if (INTEL_INFO(dev)->gen >= 6)
+		__raw_i915_write32(dev_priv, ERROR_GEN6, 0);
 
 	intel_uncore_forcewake_reset(dev, restore_forcewake);
 }
-- 
1.9.1

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