Add assert_forcewakes_active() (the complementary function to
assert_forcewakes_inactive) that documents the requirement of a
function for its callers to be holding the forcewake ref (i.e. the
function is part of a sequence over which RC6 must be prevented).
One such example is during ringbuffer reset, where RC6 must be held
across the whole reinitialisation sequence.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_ringbuffer.c | 11 ++++++++++-
drivers/gpu/drm/i915/intel_uncore.c | 12 ++++++++++++
drivers/gpu/drm/i915/intel_uncore.h | 2 ++
3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 05c08b0bc172..4285f09ff8b8 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -579,7 +579,16 @@ static int init_ring_common(struct intel_engine_cs *engine)
static void reset_ring_common(struct intel_engine_cs *engine,
struct drm_i915_gem_request *request)
{
- /* Try to restore the logical GPU state to match the continuation
+ /*
+ * RC6 must be prevented until the reset is complete and the engine
+ * reinitialised. If it occurs in the middle of this sequence, the
+ * state written to/loaded from the power context is ill-defined (e.g.
+ * the PP_BASE_DIR may be lost).
+ */
+ assert_forcewakes_active(engine->i915, FORCEWAKE_ALL);
+
+ /*
+ * Try to restore the logical GPU state to match the continuation
* of the request queue. If we skip the context/PD restore, then
* the next request may try to execute assuming that its context
* is valid and loaded on the GPU and so may try to access invalid
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index b3c3f94fc7e4..3d41667919dc 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -629,6 +629,18 @@ void assert_forcewakes_inactive(struct drm_i915_private *dev_priv)
WARN_ON(dev_priv->uncore.fw_domains_active);
}
+void assert_forcewakes_active(struct drm_i915_private *dev_priv,
+ enum forcewake_domains fw_domains)
+{
+ if (!dev_priv->uncore.funcs.force_wake_get)
+ return;
+
+ assert_rpm_wakelock_held(dev_priv);
+
+ fw_domains &= dev_priv->uncore.fw_domains;
+ WARN_ON(fw_domains & ~dev_priv->uncore.fw_domains_active);
+}
+
/* We give fast paths for the really cool registers */
#define NEEDS_FORCE_WAKE(reg) ((reg) < 0x40000)
diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h
index 66eae2ce2f29..582771251b57 100644
--- a/drivers/gpu/drm/i915/intel_uncore.h
+++ b/drivers/gpu/drm/i915/intel_uncore.h
@@ -137,6 +137,8 @@ void intel_uncore_resume_early(struct drm_i915_private *dev_priv);
u64 intel_uncore_edram_size(struct drm_i915_private *dev_priv);
void assert_forcewakes_inactive(struct drm_i915_private *dev_priv);
+void assert_forcewakes_active(struct drm_i915_private *dev_priv,
+ enum forcewake_domains fw_domains);
const char *intel_uncore_forcewake_domain_to_str(const enum forcewake_domain_id id);
enum forcewake_domains
--
2.14.2
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