Nouveau - Jun 2025 - [PATCH v2 0/6] rust: add support for port io

On Wed, May 14, 2025 at 12:58?PM Andrew Ballance
<andrewjballance at gmail.com> wrote:
>
> currently the rust `Io` type maps to the c read{b, w, l, q}/write{b, w, l,
q}
> functions and have no support for port io. this can be a problem for
pci::Bar
> because the pointer returned by pci_iomap can be either PIO or MMIO [0].
>
> this patch series splits the `Io` type into `Io`, and `MMIo`. `Io` can be
> used to access PIO or MMIO. `MMIo` can only access memory mapped IO but
> might, depending on the arch, be faster than `Io`. and updates pci::Bar,
> so that it is generic over Io and, a user can optionally give a compile
> time hint about the type of io.
>
> Link: https://docs.kernel.org/6.11/driver-api/pci/pci.html#c.pci_iomap [0]
This series seems to try and solve parts of the same problems as
Daniel's patchset:
https://lore.kernel.org/rust-for-linux/20250603-topics-tyr-platform_iomem-v9-0-a27e04157e3e
at collabora.com/#r

We should probably align these two patchsets so that they do not add
incompatible abstractions for the same thing.

Alice

On 6/16/25 10:03 AM, Alice Ryhl wrote:
> On Wed, May 14, 2025 at 12:58?PM Andrew Ballance
> <andrewjballance at gmail.com> wrote:
>>
>> currently the rust `Io` type maps to the c read{b, w, l, q}/write{b, w,
l, q}
>> functions and have no support for port io. this can be a problem for
pci::Bar
>> because the pointer returned by pci_iomap can be either PIO or MMIO
[0].
>>
>> this patch series splits the `Io` type into `Io`, and `MMIo`. `Io` can
be
>> used to access PIO or MMIO. `MMIo` can only access memory mapped IO but
>> might, depending on the arch, be faster than `Io`. and updates
pci::Bar,
>> so that it is generic over Io and, a user can optionally give a compile
>> time hint about the type of io.
>>
>> Link: https://docs.kernel.org/6.11/driver-api/pci/pci.html#c.pci_iomap
[0]
> 
> This series seems to try and solve parts of the same problems as
> Daniel's patchset:
>
https://lore.kernel.org/rust-for-linux/20250603-topics-tyr-platform_iomem-v9-0-a27e04157e3e
at collabora.com/#r
> 
> We should probably align these two patchsets so that they do not add
> incompatible abstractions for the same thing.
AFAICS, they solve different problems, i.e.

   1) Add Port I/O support to the generic I/O abstractions.
   2) Add an abstraction for generic ioremap() used to map a struct resource
      obtained from a platform device.

The patch series will conflict though, I think it would be best to rebase this
one onto Daniel's patch series, since it is close to land.