Nouveau - Aug 2014 - [PATCH 09/19] drm/radeon: handle lockup in delayed work, v2

Am 04.08.2014 um 16:40 schrieb Maarten Lankhorst:
> op 04-08-14 16:37, Christian K?nig schreef:
>>> It'a pain to deal with gpu reset.
>> Yeah, well that's nothing new.
>>
>>> I've now tried other solutions but that would mean reverting to
the old style during gpu lockup recovery, and only running the delayed work when
!lockup.
>>> But this meant that the timeout was useless to add. I think the
cleanest is keeping the v2 patch, because potentially any waiting code can be
called during lockup recovery.
>> The lockup code itself should never call any waiting code and V2
doesn't seem to handle a couple of cases correctly either.
>>
>> How about moving the fence waiting out of the reset code?
> What cases did I miss then?
>
> I'm curious how you want to move the fence waiting out of reset, when
there are so many places that could potentially wait, like radeon_ib_get can
call radeon_sa_bo_new which can do a wait, or radeon_ring_alloc that can wait on
radeon_fence_wait_next, etc.
The IB test itself doesn't needs to be protected by the exclusive lock. 
Only everything between radeon_save_bios_scratch_regs and 
radeon_ring_restore.

Christian.

op 04-08-14 16:45, Christian K?nig schreef:
> Am 04.08.2014 um 16:40 schrieb Maarten Lankhorst:
>> op 04-08-14 16:37, Christian K?nig schreef:
>>>> It'a pain to deal with gpu reset.
>>> Yeah, well that's nothing new.
>>>
>>>> I've now tried other solutions but that would mean
reverting to the old style during gpu lockup recovery, and only running the
delayed work when !lockup.
>>>> But this meant that the timeout was useless to add. I think the
cleanest is keeping the v2 patch, because potentially any waiting code can be
called during lockup recovery.
>>> The lockup code itself should never call any waiting code and V2
doesn't seem to handle a couple of cases correctly either.
>>>
>>> How about moving the fence waiting out of the reset code?
>> What cases did I miss then?
>>
>> I'm curious how you want to move the fence waiting out of reset,
when there are so many places that could potentially wait, like radeon_ib_get
can call radeon_sa_bo_new which can do a wait, or radeon_ring_alloc that can
wait on radeon_fence_wait_next, etc.
>
> The IB test itself doesn't needs to be protected by the exclusive lock.
Only everything between radeon_save_bios_scratch_regs and radeon_ring_restore.
I'm not sure about that, what do you want to do if the ring tests fail? Do
you have to retake the exclusive lock?

~Maarten

Am 04.08.2014 um 16:58 schrieb Maarten Lankhorst:
> op 04-08-14 16:45, Christian K?nig schreef:
>> Am 04.08.2014 um 16:40 schrieb Maarten Lankhorst:
>>> op 04-08-14 16:37, Christian K?nig schreef:
>>>>> It'a pain to deal with gpu reset.
>>>> Yeah, well that's nothing new.
>>>>
>>>>> I've now tried other solutions but that would mean
reverting to the old style during gpu lockup recovery, and only running the
delayed work when !lockup.
>>>>> But this meant that the timeout was useless to add. I think
the cleanest is keeping the v2 patch, because potentially any waiting code can
be called during lockup recovery.
>>>> The lockup code itself should never call any waiting code and
V2 doesn't seem to handle a couple of cases correctly either.
>>>>
>>>> How about moving the fence waiting out of the reset code?
>>> What cases did I miss then?
>>>
>>> I'm curious how you want to move the fence waiting out of
reset, when there are so many places that could potentially wait, like
radeon_ib_get can call radeon_sa_bo_new which can do a wait, or
radeon_ring_alloc that can wait on radeon_fence_wait_next, etc.
>> The IB test itself doesn't needs to be protected by the exclusive
lock. Only everything between radeon_save_bios_scratch_regs and
radeon_ring_restore.
> I'm not sure about that, what do you want to do if the ring tests fail?
Do you have to retake the exclusive lock?
Just set need_reset again and return -EAGAIN, that should have mostly 
the same effect as what we are doing right now.

Christian.
>
> ~Maarten
>