Re: [PATCH v4 3/7] drm: nova: Add chipid enum to nova-drm UAPI

[Alistair Popple]

On 2026-08-26 at 11:41 +1000, John Hubbard <jhubbard@xxxxxxxxxx> wrote...
> On 8/25/26 6:27 PM, Alistair Popple wrote:
> > On 2026-08-26 at 07:13 +1000, John Hubbard <jhubbard@xxxxxxxxxx> wrote...
> >> On 8/25/26 1:53 PM, Danilo Krummrich wrote:
> >>> On Tue Aug 25, 2026 at 9:13 AM CEST, Alistair Popple wrote:
> >> ...
> > Sure. Two questions:
> > 
> > 1) Do we also need to provide the decoded implementation value?
> 
> User space needs to:
> 
> a) Know enough about the GPU to be able to choose an SM version (and
> probably a few other things) which in turn is eventually required in
> order to run GPU programs, as shown in your merge request[1].

Right - currently that comes from either chip-id lookup table or direct decoding
of the chip-id (although [1] doesn't currently look at it). If we're not going
to allow either of those for architecture it doesn't make sense to need it for
implementation either. IOW I think kernel should provide the decoded value for
implementation too.

> b) Display GPU information to the user.
> 
> c) I'm sure to be overlooking something.
> 
> > 2) If we provide the decoded values why do we need to expose the chip-id at all?
>  OK, so maybe we don't?

Yeah, I agree. Doesn't make sense to if we're going to do the decoding in the
kernel.

 - Alistair

> [1] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/43352/diffs?commit_id=945a8e7c51939577526974b342c8dc6bafc3372f#3bb2fa8303917a2ad83e2239c2cae842dfaa594f
> 
> thanks,
> -- 
> John Hubbard
>