[PATCH] drm/radeon: make 64bit fences more robust

[Jerome Glisse]

On Mon, Sep 10, 2012 at 4:13 PM, Dave Airlie <airlied at gmail.com> wrote:
>>>>
>>>>
>>>>> It might be related to a hardware bug, or the algorithm is flawed in a
>>>>> way I currently don't see. Anyway the old code we had wasn't so picky
>>>>> about such problems and the patch just tries to make the current code as
>>>>> robust as the old code was, which indeed seems to solve the problems we see.
>>>>>
>>>>> The wrap around detection still works (tested by setting the initial
>>>>> fence value to 0xfffffff0 and letting it wrap around shortly after
>>>>> start), so I think it we can safely commit this.
>
> Can we start fences off so we wrap around after say 15-20 minutes?
> that would ensure
>
> a) its tested
> b) we see failure in a lifetime.
>
> Dave.

IIRC normal desktop with continuous activities was around 400 fence/minutes.

Anyway it all depends on what is wrong. Do we sometime get a 0 as
fence value or do we get fence value in wrong order. Depending on that
the wrap around is a different issue see my previous mails.

Cheers,
Jerome