Re: [RFC 1/2] drm/amdgpu: Store SDMA instance and index in the ring

["Timur Kristóf" <timur.kristof@gmail.com>]

On 2026. szeptember 8., kedd 10:54:04 közép-európai nyári idő Tvrtko Ursulin 
wrote:
> On 08/09/2026 09:42, Timur Kristóf wrote:
> > On 2026. június 22., hétfő 16:36:48 közép-európai nyári idő Tvrtko Ursulin
> > 
> > wrote:
> >> Instead of searching for the matching SDMA instance inside many of the
> >> SDMA ring vfuncs, lets just cache the instance and index in the new SDMA
> >> specific section of struct amdgpu_ring. This converts a function call
> >> plus
> >> array walks to a direct lookup.
> > 
> > AFAIK, the rings already have the IP block instance ID in the "me" field.
> > So this could be simplified by using that. For example like this:
> > https://pastebin.com/raw/jp4Uk2sE
> 
> Ah thank you, it never occurred to me ring->me is not a management
> engine of some sort but ring's personal pronoun. :)

I think the field should be better documented. AFAIU, it refers to the firmware 
instance that handles the ring. For SDMA it's the same as the instance ID.

(For graphics/compute this is the "micro engine" CP (command processor) 
instance. There is only one graphics/compute IP block and there are several CP 
instance within that same IP block.)

In your words, "on a rainy day" we can write that documentation or just rename 
the field to something more meaningful. :)
 
> >> While at it, we also consolidate the initialization side with a new
> >> amdgpu_sdma_ring_init() helper.
> > 
> > Can you move that part to a separate commit?
> 
> Yes that makes much more sense indeed, will do.

Thanks!