[PATCH 3/8] drm/i915: Verify GT workaround state after GPU init

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Since we now have all the GT workarounds in a table, by adding a simple
shared helper function we can now verify that their values are still
applied after some interesting events in the lifetime of the driver.

Initially we only do this after GPU initialization.

v2:
 Chris Wilson:
 * Simplify verification by realizing it's a simple xor and and.
 * Remove verification from engine reset path.
 * Return bool straight away from the verify API.

v3:
 * API rename. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.c          |  1 +
 drivers/gpu/drm/i915/i915_gem.c          |  3 +++
 drivers/gpu/drm/i915/intel_workarounds.c | 34 ++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_workarounds.h |  2 ++
 4 files changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6f497cf31ffc..b310a897a4ad 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -53,6 +53,7 @@
 #include "i915_vgpu.h"
 #include "intel_drv.h"
 #include "intel_uc.h"
+#include "intel_workarounds.h"
 
 static struct drm_driver driver;
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6333a7d6af5a..298f79c137eb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5334,7 +5334,10 @@ int i915_gem_init_hw(struct drm_i915_private *dev_priv)
 		I915_WRITE(MI_PREDICATE_RESULT_2, IS_HSW_GT3(dev_priv) ?
 			   LOWER_SLICE_ENABLED : LOWER_SLICE_DISABLED);
 
+	/* Apply the GT workarounds... */
 	intel_gt_apply_workarounds(dev_priv);
+	/* ...and determine whether they are sticking. */
+	intel_gt_verify_workarounds(dev_priv, "init");
 
 	i915_gem_init_swizzling(dev_priv);
 
diff --git a/drivers/gpu/drm/i915/intel_workarounds.c b/drivers/gpu/drm/i915/intel_workarounds.c
index 847988d15e8a..592226a0c711 100644
--- a/drivers/gpu/drm/i915/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/intel_workarounds.c
@@ -977,6 +977,40 @@ void intel_gt_apply_workarounds(struct drm_i915_private *dev_priv)
 	wa_list_apply(dev_priv, &dev_priv->gt_wa_list);
 }
 
+static bool
+wa_verify(const struct i915_wa *wa, u32 cur, const char *name, const char *from)
+{
+	if ((cur ^ wa->val) & wa->mask) {
+		DRM_ERROR("%s workaround lost on %s! (%x=%x/%x, expected %x, mask=%x)\n",
+			  name, from, i915_mmio_reg_offset(wa->reg), cur,
+			  cur & wa->mask, wa->val, wa->mask);
+
+		return false;
+	}
+
+	return true;
+}
+
+static bool wa_list_verify(struct drm_i915_private *dev_priv,
+			   const struct i915_wa_list *wal,
+			   const char *from)
+{
+	struct i915_wa *wa;
+	unsigned int i;
+	bool ok = true;
+
+	for (i = 0, wa = wal->list; i < wal->count; i++, wa++)
+		ok &= wa_verify(wa, I915_READ(wa->reg), wal->name, from);
+
+	return ok;
+}
+
+bool intel_gt_verify_workarounds(struct drm_i915_private *dev_priv,
+				 const char *from)
+{
+	return wa_list_verify(dev_priv, &dev_priv->gt_wa_list, from);
+}
+
 struct whitelist {
 	i915_reg_t reg[RING_MAX_NONPRIV_SLOTS];
 	unsigned int count;
diff --git a/drivers/gpu/drm/i915/intel_workarounds.h b/drivers/gpu/drm/i915/intel_workarounds.h
index 979695a53964..8822e6035f8d 100644
--- a/drivers/gpu/drm/i915/intel_workarounds.h
+++ b/drivers/gpu/drm/i915/intel_workarounds.h
@@ -32,6 +32,8 @@ int intel_ctx_workarounds_emit(struct i915_request *rq);
 
 void intel_gt_init_workarounds(struct drm_i915_private *dev_priv);
 void intel_gt_apply_workarounds(struct drm_i915_private *dev_priv);
+bool intel_gt_verify_workarounds(struct drm_i915_private *dev_priv,
+				 const char *from);
 
 void intel_whitelist_workarounds_apply(struct intel_engine_cs *engine);
 
-- 
2.19.1