Re: [PATCH v5 01/38] gpu: nova-core: fix aux device registration for multi-GPU systems

[Danilo Krummrich]

On Fri Feb 27, 2026 at 4:41 PM CET, Gary Guo wrote:
> On Fri Feb 27, 2026 at 3:37 PM GMT, Gary Guo wrote:
>> On Tue Feb 24, 2026 at 2:47 PM GMT, Danilo Krummrich wrote:
>>> On 2/21/26 3:09 AM, John Hubbard wrote:
>>>> The auxiliary device registration was using a hardcoded ID of 0, which
>>>> caused probe() to fail on multi-GPU systems with:
>>>> 
>>>>    sysfs: cannot create duplicate filename '/bus/auxiliary/devices/NovaCore.nova-drm.0'
>>>> 
>>>> Fix this by using an atomic counter to generate unique IDs for each
>>>> GPU's aux device registration. The TODO item to eventually use XArray
>>>> for recycling aux device IDs is retained, but for now, this works very
>>>> nicely.
>>>> 
>>>> This has the side effect of making debugfs[1] work on multi-GPU systems.
>>>> 
>>>> [1] https://lore.kernel.org/20260203224757.871729-1-ttabi@xxxxxxxxxx
>>>> 
>>>> Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>
>>>> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
>>>
>>> Applied to drm-rust-next, thanks!
>>>
>>>     [ Use LKMM atomics; inline and slightly reword TODO comment. - Danilo ]
>>
>> Danilo, can you drop this patch from drm-rust-next?
>>
>> The patch that is supposed to be queued is
>> https://lore.kernel.org/rust-for-linux/20260205221758.219192-1-jhubbard@xxxxxxxxxx/#t,
>> which does correctly use LKMM atomics and add comments about possible use of
>> XArray.
>>
>> In fact, I am not sure why this patch carries my R-b.
>
> Hmm, actually this patch contains updated comment but somehow have LKMM atomics
> changed back to Rust atomics. Not sure what happens. Anyhow that patch should be
> picked instead.

I picked up the latest version of this patch and fixed up the LKMM atomics, i.e.
the result should be correct:

https://gitlab.freedesktop.org/drm/rust/kernel/-/commit/d3f36fa57aa289c43e01da16c928a2cd971ad5dc

Looks like I could have picked v2 instead, as it seems to be identical except
that it already uses LKMM atomics.

@John: For the future, please don't send patches in multiple series / ways. I
think there was no reason to include the patch in this series in the first
place.

Thanks,
Danilo