[PATCH 1/1] drm/amdgpu: Use GTT for dumb buffer if sg display enabled

[Deepak Sharma]

On 05/22/2018 05:12 AM, Christian König wrote:
> [SNIP]
>>> If the BO is moved from VRAM to VRAM (to make it linear) or from VRAM to
>>> GTT for scanout doesn't really matter.
>> Not sure what you mean. Dumb BOs are only used for CPU access and
>> scanout, and should be created accordingly.
> 
> Well what I wanted to say is that it isn't worse than before.
> 
> On the other hand thinking about it something like 5 lines of code 
> sounds to avoid the extra copy sounds reasonable to me.
> 
Thanks, I missed that point , Will use amdgpu_display_supported_domains 
as suggested and push v2.

>>> And BTW GTT BOs used for scanout should be created USWC, so the argument
>>> that it is faster for CPU access isn't really true either.
>> You're saying scanout doesn't work from cacheable GTT BOs? If it does
>> work, it would be preferable for dumb BOs.
> 
> Well, scanout does seem to work from cachable GTT BOs. But from the 
> documentation from the hardware team I'm pretty sure they never 
> validated this.
> 
> And as usually nobody from the hardware guys I asked so far could give 
> me a clear answer if it works or not.
> 
FWIW, I tested this on Stoney with Cros where dumb buffers used for 
splash screen, Its working fine.


> Regards,
> Christian.

Thanks,
Deepak