[Intel-gfx] [PATCH 05/17] drm/i915: Move ring_begin to signal()

[Ben Widawsky]

On Sat, Dec 14, 2013 at 09:05:03AM +0000, Chris Wilson wrote:
> On Fri, Dec 13, 2013 at 08:15:53PM -0800, Ben Widawsky wrote:
> > Add_request has always contained both the semaphore mailbox updates as
> > well as the breadcrumb writes. Since the semaphore signal is the one
> > which actually knows about the number of dwords it needs to emit to the
> > ring, we move the ring_begin to that function. This allows us to remove
> > the hideously shared #define
> 
> We can now just split it up and use two intel_ring_begin(). And there is
> no reason not to pack the semaphore commands tightly.
> -Chris

Tight packing comes in a later patch.

I thought about multi ring begins, except I couldn't figure out a way to
easily back out if a later one fails. It would be a shame to emit
some/none of the semaphore updates, and then success on the
breadcrumb/MI_USER_INTERRUPT (or vice versa).

-- 
Ben Widawsky, Intel Open Source Technology Center