On Wed, Jun 18, 2014 at 05:16:03PM +0100, oscar.mateo@xxxxxxxxx wrote: > From: Oscar Mateo <oscar.mateo@xxxxxxxxx> > > The original comment that introduced it said: > > commit 0009e46cd54324c4af20b0b52b89973b1b914167 > Author: Ben Widawsky <ben@xxxxxxxxxxxx> > Date: Fri Dec 6 14:11:02 2013 -0800 > > drm/i915: Track which ring a context ran on > > Previously we dropped the association of a context to a ring. It is > however very important to know which ring a context ran on (we could > have reused the other member, but I was nitpicky). > > This is very important when we switch address spaces, which unlike > context objects, do change per ring. > > As an example, if we have: > > RCS BCS > ctx A > ctx A > ctx B > ctx B > > Without tracking the last ring B ran on, we wouldn't know to switch the > address space on BCS in the last row. > > But this is not really true, because we are already checking to != from (with > "from" being = ring->last_context) and that should be enough to make sure we > switch to the right address space. > > We would have a problem if we switched the context object for every ring (since > then we would fail to do it in some situations) but we only switch it for the > render ring, so we don't care. > > Signed-off-by: Oscar Mateo <oscar.mateo@xxxxxxxxx> I have sent the very same patch, so Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
