[PATCH 1/6] drm/i915: Force the switch to the i915->kernel_context
Chris Wilson
chris at chris-wilson.co.uk
Fri Nov 3 11:32:32 UTC 2017
In the next few patches, we will have a hard requirement that we emit a
context-switch to the perma-pinned i915->kernel_context (so that we can
save the HW state using that context-switch). As the first context
itself may be classed as a kernel context, we want to be explicit in our
comparison. For an extra-layer of finesse, we can check the last
unretired context on the engine; as well as the last retired context
when idle.
v2: verbose verbosity
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
drivers/gpu/drm/i915/intel_engine_cs.c | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index ddbe5c9bf45a..cd3a27e6d313 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1585,10 +1585,33 @@ bool intel_engines_are_idle(struct drm_i915_private *dev_priv)
return true;
}
+/**
+ * intel_engine_has_kernel_context:
+ * @engine: the engine
+ *
+ * Returns true if the last context to be executed on this engine is the kernel
+ * context (#i915.kernel_context).
+ *
+ * One quirk is that if no request has ever been executed on the engine;
+ * that is treated as being equivalent to the having the kernel context loaded.
+ */
bool intel_engine_has_kernel_context(const struct intel_engine_cs *engine)
{
- return (!engine->last_retired_context ||
- i915_gem_context_is_kernel(engine->last_retired_context));
+ const struct i915_gem_context * const kernel_context =
+ engine->i915->kernel_context;
+ struct drm_i915_gem_request *rq;
+
+ lockdep_assert_held(&engine->i915->drm.struct_mutex);
+
+ /* An unretired request? */
+ rq = __i915_gem_active_peek(&engine->timeline->last_request);
+ if (rq)
+ return rq->ctx == kernel_context;
+
+ if (!engine->last_retired_context)
+ return true;
+
+ return engine->last_retired_context == kernel_context;
}
void intel_engines_reset_default_submission(struct drm_i915_private *i915)
--
2.15.0
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