[Intel-gfx] [PATCH v4] drm/i915: clarify semaphore-ring interaction

[Ben Widawsky]

On Mon, 21 May 2012 09:44:02 +0100
Chris Wilson <chris at chris-wilson.co.uk> wrote:

> On Sun, 20 May 2012 08:45:38 -0700, Ben Widawsky <ben at bwidawsk.net> wrote:
> > After Daniel split out this code, I think this makes more sense, and
> > looks nicer. Also added some comments to help the situation.
> > 
> > v2: Make signal_mbox be all rings for symmetric-ness.
> > v3: submitted the wrong version of the patch before.
> >   v2 had an issue with odd number of rings. The fix is to always emit an
> >   even number of instructions to the ring with mbox updates.
> > v4: I suck. The code should send out mbox updates for NUM_RINGS-1 *
> >   number of commands. Instead of NUM_RINGS * number of commands-1.
> > -ret = intel_ring_begin(ring, round_up((I915_NUM_RINGS) * 3, 2) + 4);
> > +ret = intel_ring_begin(ring, round_up((I915_NUM_RINGS-1) * 4, 2) + 4);
> 
> I'm honestly less enthralled about v4. I'd rather see that as a separate
> preparatory patch so that it is put into context.
> -Chris
> 

I can do that. Are you okay with the idea otherwise? This is really all
prep work for some HSW patches anyway.

-- 
Ben Widawsky, Intel Open Source Technology Center