From: Matthew Brost Date: Thu, 14 Oct 2021 17:19:44 +0000 (-0700) Subject: drm/i915/guc: Don't call switch_to_kernel_context with GuC submission X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3633242927101b4bcff14cb0f718ecd4d346c5b1;p=linux.git drm/i915/guc: Don't call switch_to_kernel_context with GuC submission Calling switch_to_kernel_context isn't needed if the engine PM reference is taken while all user contexts are pinned as if don't have PM ref that guarantees that all user contexts scheduling is disabled. 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 v3: (John Harrison) - Update commit message - Fix workding comment Signed-off-by: Matthew Brost Reviewed-by: Daniel Vetter Reviewed-by: John Harrison Signed-off-by: John Harrison Link: https://patchwork.freedesktop.org/patch/msgid/20211014172005.27155-5-matthew.brost@intel.com --- diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c index dacd627737359..a1334b48dde7b 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c @@ -162,6 +162,19 @@ static bool switch_to_kernel_context(struct intel_engine_cs *engine) unsigned long flags; bool result = true; + /* + * This is execlist specific behaviour intended to ensure the GPU is + * idle by switching to a known 'safe' context. With GuC submission, the + * same idle guarantee is achieved by other means (disabling + * scheduling). Further, switching to a 'safe' context has no effect + * with GuC submission as the scheduler can just switch back again. + * + * FIXME: Move this backend scheduler specific behaviour into the + * scheduler 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;