Re: [PATCH 2/2] rust: scatterlist: honor the device's maximum segment size

[Alexandre Courbot]

On Mon Sep 28, 2026 at 7:44 AM JST, Matteo Kloiber wrote:
> First of all, thanks for merging my first two patches and sorry about my late reply.
>
> What I think Alex meant and what I agree with is that the new API should focus on
> making semantic bugs harder, not to necessarily make it easier to write safer
> drivers. That being said, I think we can do both with this change.
>
> The key change here is that we introduce a structure that defines dma
> parameters for a device. This structure deliberately has no default
> implementation and new fields should be added even if they require changes for
> all dma drivers.
<...>

Thanks for the detailed plan; I think it mostly makes sense.

A few details that we have discussed offline with Danilo:

- The `probe` methods should not take the `dma::Setup` token directly,
  but rather a bus-specific struct that contains it and can be augmented
  with other capabilities. Drivers would have to deconstruct it using
  the `..` operator to make sure code doesn't break if we add new tokens
  to it.
- The token should not assume default parameters and only call functions
  corresponding to parameters explicitly set; converting the token to a
  handler means the driver acknowledged all the settings, so we should
  not make any parameter mandatory (the doc should of course detail what
  drivers *should* do).

With that and your plan I believe you have a solid basis to send a
RFC/PoC. :)