[Intel-gfx] [PATCH] drm/i915: Handle sync_seqno correctly when seqno has wrapped.

[Mika Kuoppala]

On Mon, 19 Nov 2012 09:21:48 -0800, Ben Widawsky <ben at bwidawsk.net> wrote:
> On Mon, 19 Nov 2012 12:55:22 +0200
> Mika Kuoppala <mika.kuoppala at linux.intel.com> wrote:
> 
> > 
> > On Tue, 13 Nov 2012 08:39:26 -0800, Ben Widawsky <ben at bwidawsk.net> wrote:
> > > Can you add another patch on top of this to have the starting seqno be a
> > > near pre-wrap value so we can catch bugs even without igt.
> > 
> > I tried that but failed. I suspect that there is something in hw/sw
> > that doesn't like if first seqno is >0x80000000. Something in hw needs
> > to initialized explicitly if seqno is not starting from 1?
> > 
> 
> Nothing that I am aware of. If you have the first be 0, and then add a
> huge jump right after that, does it work?

We can't jump more than 0x80000000-1 as i915_seqno_passed() breaks.
But with the patches for preallocate seqnos now in, I was able to
get things working when first seqno was 0xFFFF0000. 

-Mika