AMDGPU's rings VS Radeon's

[Alexandre Demers]

Hi,

For those who know, I'm still working on VCE1 enablement under AMDGPU.
Progress is happening, slowly but surely. While investigating the ring init
calls, a few elements catched my attention and I'd like some help in
figuring out the differences between AMDGPU's ring sizes and Radeon's ones.

1- I understand that the size parameter changed from bytes
under radeon_ring_init to dword under amdgpu_ring_init. That being said,
some values don't seem to be equivalent between Radeon and AMDGPU. For
example, GFX ring size went from 1024 * 1024 bytes to 1024 dwords (for most
GFX versions), which seems off even when taking into account how
amdgpu_ring_init calculates the final allocated size. This question is more
about understanding than a problem strictly speaking.

2- Under AMDGPU, SI's GFX (GFX6) ring size is 2048, while this value is
1024 for all the other GFX versions. Under Radeon, the GFX ring size values
are all the same (1024 * 1024) under Evergreen/SI/CIK/NI and others. Is
there any reason why SI's GFX6 ring size would be twice the size of the
other values under AMDGPU?

3- Would it be acceptable to add names to rings under Radeon, the same
names as the ones used under AMDGPU? I think it is more talkative for the
average user and for debugging purposes to deal with ring names than
indexes. I already have patches in my code to address this suggestion.

That's all for now.

Cheers
Alexandre Demers
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