[Intel-gfx] i915 resume-from-hibernation problems on resume with current Linus' tree

[Jiri Kosina]

On Mon, 10 Mar 2014, Daniel Vetter wrote:

> >> > *ERROR* render ring initialization failed ctl 0001f001 head 00003004 tail 00000000 start 00003000
> >> >
> >> > as it doesn't seem to be there in case of resumption that works properly.
> >> >
> >> > Please see the dmesg from the broken case below.
> >>
> >> I encountered this again with -rc5.
> >>
> >> If there is anything I can do to help debug this, please let me know.
> >
> > I hate to be doing this, but ... ping? :)
> 
> gm45 and rendering ring init failures. We've seen this occasionally
> crop up due to rather unrelated changes. Some even hit stable
> backports and had to be backed out again. We essentially have no clue
> what's amiss, but it seems to /mostly/ work. Thus far I've only hear
> reports of this for gm45 and not yet really for upstream. Until
> someone digs up more evidence I think we need to classify this as a
> rare heisenbug and not really a regression :(

Thanks for getting back to me with this, Daniel.

Well, this started to be rather regular sometime during the 3.14 
development cycle on my system.

I am able to reproduce it after ~20 suspend-resume cycles. Which is rather 
inconvenient for bisect, but enough for making the kernel unusable on that 
system.

> One thing we could try is to simply repeat the ring init setup, maybe
> after a gpu reset or something like that.

Will be happy to test any patches.

Thanks,

-- 
Jiri Kosina
SUSE Labs