[PATCH] [RFC] drm/radeon: clear WC flag when moving bo from vram to gtt

[Michel Dänzer]

On 24/04/17 06:51 PM, Christian König wrote:
> Am 24.04.2017 um 11:42 schrieb Julien Isorce:
>> But re-add the flag is the bo is moved back to vram.
>>
>> This fixes "ring 0/3 stalled" issue which happens when the driver
>> evicts bo from vram to gtt, at least on TAHITI and CAPVERDE.
> 
> Interesting find, but NAK on the approach for fixing it.
> 
> If WC mappings don't work for TAHITI and CAPVERDE we need to figure out
> why or at least disable them for those hardware generations in general.
> 
> Disabling WC for BOs swapped out from VRAM won't buy us much if the BO
> was initially created in GTT anyway.

Moreover, RADEON_GEM_GTT_WC shouldn't have any effect at all for a BO
which is currently in VRAM, so it's not clear how the patch makes any
difference. I suspect it might accidentally cause RADEON_GEM_GTT_WC to
be ignored altogether in radeon_vm_bo_update and/or
radeon_ttm_placement_from_domain.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer