Re: [PATCH] [rfc] drm/radeon/kms: pm debugging check for vbl.

[Dave A. <ai...@gm...>]

2010/2/18 Rafał Miłecki <za...@gm...>:
> W dniu 18 lutego 2010 09:28 użytkownik Dave Airlie <ai...@gm...> napisał:
>>>
>>>> It adds some reading & printing steps before every reclock, while we
>>>> really want it to happen as soon as possible. Maybe you could execute
>>>> this only on some
>>
>> btw you won't get the print if you are in vblank, and if you aren't
>> well the print
>> doesn't matter, I'm also thinking the engine change reads/writes a lot of regs,
>> so two more might not matter so much.
>
> Yeah, maybe that's right.
>
> While your idea of testing being in VBLANK is "sane" :) it could
> happen we start reclocking in VBLANK (first test will pass), we
> reclock out of VBLANK (not wanted, possible corruption), and we hit
> next VBLANK in second test.
>
> In such situation (machine) I'm sure we will hit "false" in test
> anyway (sooner or later) but maybe we could improve in anyway somehow?
> To make sure it's sill the same VBLANK?

That could be possible, though if a reclock takes a full scanout to
operate we've
got other issues as it would never be possible by the sounds of it.

The check on the way out could be toned down alright, its probably not
as important,

btw I've still got problems even with that other patch applied, I get
reclocking in
 the middle of the frame,

Reverting 73a6d3fc104827db574e4bd206a025299fef0bb1
drm/radeon/kms: use wait queue (events) for VBLANK sync

still fixes it for me here.

Dave.