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

[Christian König]

[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.

>> 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.

Regards,
Christian.