Quoting Mika Kuoppala (2017-08-21 10:17:52) > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > > > During suspend we want to flush out all active contexts and their > > rendering. To do so we queue a request from the kernel's context, once > > we know that request is done, we know the GPU is completely idle. To > > speed up that switch bump the GPU clocks. > > > > Switching to the kernel context prior to idling is also used to enforce > > a barrier before changing OA properties, and when evicting active > > rendering from the global GTT. All cases where we do want to > > race-to-idle. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/i915_gem_context.c | 11 ++++++++--- > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c > > index 58a2a44f88bd..ca1423ad2708 100644 > > --- a/drivers/gpu/drm/i915/i915_gem_context.c > > +++ b/drivers/gpu/drm/i915/i915_gem_context.c > > @@ -895,6 +895,7 @@ int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv) > > > > for_each_engine(engine, dev_priv, id) { > > struct drm_i915_gem_request *req; > > + bool active = false; > > int ret; > > > > if (engine_has_kernel_context(engine)) > > @@ -913,13 +914,17 @@ int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv) > > prev = i915_gem_active_raw(&tl->last_request, > > &dev_priv->drm.struct_mutex); > > if (prev) > > - i915_sw_fence_await_sw_fence_gfp(&req->submit, > > - &prev->submit, > > - GFP_KERNEL); > > + active |= i915_sw_fence_await_sw_fence_gfp(&req->submit, > > + &prev->submit, > > + GFP_KERNEL) > 0; > > There is no point of kicking the clocks if we are the only request left? > > Well logical as the request is empty, just pondering if the actual ctx > save/restore would finish quicker. I was thinking if it was just the context save itself, it not would be enough of a difference to justify itself. Just gut feeling and not measured, I worry about the irony of boosting from idle just to idle. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx