[PATCH 3/3] drm/amdgpu/vcn: Add parameter to force (en/dis)abling indirect SRAM mode

[Guilherme G. Piccoli]

On 16/01/2023 20:00, Alex Deucher wrote:
> [...]
> 
> It's not clear to me when this would be used.  We only disable it
> briefly during new asic bring up, after that we never touch it again.
> No end user on production hardware should ever have to change it and
> doing so would break VCN on their system.
> 
> Alex

[+ Pierre-Loup]

Steam Deck is facing a pretty weird scenario then heheh

Commit 82132ecc543 ("drm/amdgpu: enable Vangogh VCN indirect sram mode")
corrected a long-term issue in which the indirect SRAM mode wasn't
enabled for Vangogh - and Deck GPU architecture is Vangogh, so it was
working perfectly with that disabled.

Happens that a bad FW candidate seems to have broken something - it was
a bit convoluted to debug, but we proved that disabling indirect SRAM is
a good workaround so far, it "restored the behavior" pre-82132ecc543.

Hence my proposal - this parameter would've made life so much easier,
and we're start using it "downstream" now. While I understand that of
course the FW should be fixed, meanwhile this is a cheap solution to
allow further debug and real use of the system.

Thanks,


Guilherme