[PATCH v3 1/3] drm/radeon: take exclusive_lock in read mode during, ring tests, v3

[Maarten Lankhorst]

Op 19-08-14 om 15:06 schreef Christian König:
> Am 19.08.2014 um 14:22 schrieb Maarten Lankhorst:
>> This is needed for the next commit, because the lockup detection
>> will need the read lock to run.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at canonical.com>
>> ---
>> radeon_pm_compute_clocks already checks if dpm is enabled, so no need to check a second time.
>>
>> Because of locking and waiting stuff the radeon_pm_compute_clocks and resume_force_mode calls
>> have to be done with read lock held.
>>
>> Seems to survive on my radeon when catting /sys/kernel/debug/dri/0/radeon_gpu_reset although
>> uvd fails to reset, and that ring gets disabled as a result.
>
> Depending on what hardware you have it's normal that UVD doesn't reset properly. I still haven't figured out the correct sequence in which I need to disable/enable the different UVD blocks on all hardware generations.
>
> It seems to work fine on my Cayman, but doesn't for example on Turks (which at least theoretically should have the same UVD block). It should be fine as long as the engines gets properly disabled when the IB test fails after an reset.
>
> Another common source of reset instability is DPM, while it now seems to be stable on NI and BTC I can't get a single reset to work once I use it.
Ah, in my testing I've hit both (on redwood). :-) But with DPM failures far less frequent than UVD failures, which trigger consistently.

Turks had some issues before, but my laptop completely fails early during boot with 3.17-rc1 so I can't test it.

~Maarten