[Intel-gfx] [PATCH] drm/i915: Do not add an interrupt for a context switch

[Chris Wilson]

On Thu, Aug 08, 2013 at 01:18:18AM +0200, Daniel Vetter wrote:
> Afaict the request holds a ref on the context, and that a ref on the hw
> context bo. But the active list itself (thanks to the move_to_active)
> should also hold a ref to the hw context bo, so I don't think we really
> need full request here. The old context might disappear, but no one really
> cares if it disappears a notch too early since the backing storage will
> survive long enough.

The next request holds a ref to the new context. We care about holding a
ref to the old context until the hw has finished writing to it. That is
the purpose of taking a request here, to bump the old_ctx->bo->active
for the context save. Otherwise the backing storage is liable to disappear
too early (and the hw write to a random location).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre