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

[Chris Wilson <chris@chris-wilson.co.uk>]

On Sun, 20 May 2012 08:45:38 -0700, Ben Widawsky <ben@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

-- 
Chris Wilson, Intel Open Source Technology Centre