Re: [PATCH v2] rust: dma: allow drivers to tune max segment size

[Dirk Behme <dirk.behme@gmail.com>]

On 23.01.26 14:13, Beata Michalska wrote:
> Make dma_set_max_seg_size() available to Rust so drivers can perform
> standard DMA setup steps.
> 
> Signed-off-by: Beata Michalska <beata.michalska@arm.com>
> ---
> 
> v2:
> - Aligned safety requirements
> 
>  rust/helpers/dma.c |  5 +++++
>  rust/kernel/dma.rs | 17 +++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/rust/helpers/dma.c b/rust/helpers/dma.c
> index 2afa32c21c94..220b9308830f 100644
> --- a/rust/helpers/dma.c
> +++ b/rust/helpers/dma.c
> @@ -40,3 +40,8 @@ size_t rust_helper_dma_max_mapping_size(struct device *dev)
>  {
>  	return dma_max_mapping_size(dev);
>  }
> +
> +void rust_helper_dma_set_max_seg_size(struct device *dev, unsigned int size)
> +{
> +	dma_set_max_seg_size(dev, size);
> +}

I was about to ask "please add __rust_helper" [1]. But looking into
driver-core-next it looks like some of the function in dma.c have
__rust_helper (from [1]) and some don't (from [2]). Is this by
intention or was this an omission in [2]?

Best regards

Dirk

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core.git/commit/rust/helpers/dma.c?h=driver-core-next&id=8a03afe94763108537e33b48378bbc7472b4cc9d

[2]
https://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core.git/commit/rust/helpers/dma.c?h=driver-core-next&id=d8932355f8c5673106eca49abd142f8fe0c1fe8b