Re: [PATCH 1/2] gpu: nova-core: use kernel lossless integer conversion module

["Alexandre Courbot" <acourbot@nvidia.com>]

On Fri Aug 28, 2026 at 9:09 PM JST, Danilo Krummrich wrote:
> (Cc: Miguel)
>
> On Fri Aug 28, 2026 at 7:33 AM CEST, Alexandre Courbot wrote:
>> The `kernel` crate now features a replacement for our lossless integer
>> conversion routines. Switch to the kernel version and remove our own.
>>
>> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>> Reviewed-by: Danilo Krummrich <dakr@kernel.org>
>> Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
>> ---
>>  drivers/gpu/nova-core/falcon.rs                    |  12 +-
>>  drivers/gpu/nova-core/falcon/fsp.rs                |   4 +-
>>  drivers/gpu/nova-core/fb.rs                        |   2 +-
>>  drivers/gpu/nova-core/fb/hal/gb100.rs              |   6 +-
>>  drivers/gpu/nova-core/firmware.rs                  |   4 +-
>>  drivers/gpu/nova-core/firmware/booter.rs           |   4 +-
>>  drivers/gpu/nova-core/firmware/fwsec.rs            |   2 +-
>>  drivers/gpu/nova-core/firmware/fwsec/bootloader.rs |   4 +-
>>  drivers/gpu/nova-core/firmware/gsp.rs              |   9 +-
>>  drivers/gpu/nova-core/firmware/tlv.rs              |  11 +-
>>  drivers/gpu/nova-core/fsp.rs                       |   8 +-
>>  drivers/gpu/nova-core/gsp.rs                       |   4 +-
>>  drivers/gpu/nova-core/gsp/cmdq.rs                  |  22 +--
>>  drivers/gpu/nova-core/gsp/fw.rs                    |  42 ++--
>>  drivers/gpu/nova-core/gsp/fw/commands.rs           |   4 +-
>>  drivers/gpu/nova-core/gsp/sequencer.rs             |   2 +-
>>  drivers/gpu/nova-core/mctp.rs                      |   8 +-
>>  drivers/gpu/nova-core/num.rs                       | 211 ---------------------
>>  drivers/gpu/nova-core/vbios.rs                     |   2 +-
>>  19 files changed, 78 insertions(+), 283 deletions(-)
>
> Please see the discussion in [1].
>
> If we make this change, then the subsequent conversion to const_as!() would need
> to go through the Rust tree next cycle, which could be a bit of a mess, as I'd
> expect a bunch of conflicts.
>
> Alternatively, we could the the full three cycle dance, or have a signed tag for
> const_as!() and use it right away.
>
> But honestly, the former would just be unnecessary noise. If we don't do the
> latter, let's just keep the nova-core num module until the dust has been
> settled.
>
> [1] https://lore.kernel.org/all/CANiq72k+-fNWZCwGuQ=FTchxgm-X-f6WR=tG=Ercn19ic1edQg@mail.gmail.com/

Maybe I am missing something, but wouldn't the following work?

- rc1 gets tagged, `drm-rust-next` gets the `num::casts` module,
- This series gets applied to `drm-rust-next`, then `cv!` (without the
  nova-core conversion patch) in `rust-next`,
- We wait one cycle for `cv!` to trickle down to `drm-rust-next` before
  converting nova-core to use `cv!`.

Would that work? This series doesn't overlap with the const conversions
that `cv!` covers on purpose, and it would have the benefit of getting
rid of the local `num` module in nova-core quickly.