On Mon, Aug 11, 2025 at 6:22 PM Alex Deucher <alexdeuc...@gmail.com> wrote:
> On Mon, Aug 11, 2025 at 6:08 PM Alexandre Demers > <alexandre.f.dem...@gmail.com> wrote: > > > > 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. > > You can make the ring any size you want. It's specified in the queue > descriptor. I don't remember why we picked the sizes we did in radeon > off hand. > > OK, thanks > > > > 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? > > > > From the git history: > commit 97041ed37718dc9ba30aa23ca74093dc93ac89fb > Author: Bas Nieuwenhuizen <b...@basnieuwenhuizen.nl> > Date: Thu Apr 13 16:22:51 2023 +0200 > > drm/amdgpu: Increase GFX6 graphics ring size. > > To ensure it supports 192 IBs per submission, so we can keep a > simplified IB limit in the follow up patch without having to > look at IP or GPU version. > > Reviewed-by: Christian König <christian.koe...@amd.com> > Signed-off-by: Bas Nieuwenhuizen <b...@basnieuwenhuizen.nl> > Signed-off-by: Alex Deucher <alexander.deuc...@amd.com> > > > > > 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. > > > > If you think there is value there. It seems like it would generate a > lot of churn in that driver for little gain. > > Alex > > The patches are pretty simple and straightforward. I'll send them. Cheers! Alexandre Demers > That's all for now. > > > > Cheers > > Alexandre Demers >
