[Intel-gfx] [PATCH 07/27] drm/i915/guc: Don't call switch_to_kernel_context with GuC submission

Matthew Brost
2021-08-20T22:51:34Z

Calling switch_to_kernel_context isn't needed if the engine PM reference
is taken while all contexts are pinned. By not calling
switch_to_kernel_context we save on issuing a request to the engine.

v2:
(Daniel Vetter)
- Add FIXME comment about pushing switch_to_kernel_context to backend

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/i915/gt/intel_engine_pm.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
index 1f07ac4e0672..11fee66daf60 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -162,6 +162,15 @@ static bool switch_to_kernel_context(struct intel_engine_cs *engine)
unsigned long flags;
bool result = true;

+ /*
+ * No need to switch_to_kernel_context if GuC submission
+ *
+ * FIXME: This execlists specific backend behavior in generic code, this
+ * should be pushed to the backend.
+ */
+ if (intel_engine_uses_guc(engine))
+ return true;
+
/* GPU is pointing to the void, as good as in the kernel context. */
if (intel_gt_is_wedged(engine->gt))
return true;
--
2.32.0