Re: [PATCH 2/7] iio: backend: add support for data size set

[David Lechner <dlechner@baylibre.com>]

On Mon, Sep 23, 2024 at 12:16 PM Antoniu Miclaus
<antoniu.miclaus@analog.com> wrote:
>
> Add backend support for setting the data size used.
>
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---
>  drivers/iio/industrialio-backend.c | 21 +++++++++++++++++++++
>  include/linux/iio/backend.h        |  3 +++
>  2 files changed, 24 insertions(+)
>
> diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
> index 53ab6bc86a50..a6a6bedce7f1 100644
> --- a/drivers/iio/industrialio-backend.c
> +++ b/drivers/iio/industrialio-backend.c
> @@ -473,6 +473,27 @@ int iio_backend_interface_type_get(struct iio_backend *back,
>  }
>  EXPORT_SYMBOL_NS_GPL(iio_backend_interface_type_get, IIO_BACKEND);
>
> +/**
> + * iio_backend_data_size_set - set the data width/size in the data bus.
> + * @back: Backend device
> + * @size: Size in bits
> + *
> + * Some frontend devices can dynamically control the word/data size on the
> + * interface/data bus. Hence, the backend device needs to be aware of it so
> + * data can be correctly transferred.
> + *
> + * RETURNS:
> + * 0 on success, negative error number on failure.
> + */
> +ssize_t iio_backend_data_size_set(struct iio_backend *back, ssize_t size)

Why signed size? When will it be < 0?

> +{
> +       if (!size)
> +               return -EINVAL;
> +
> +       return iio_backend_op_call(back, data_size_set, size);
> +}
> +EXPORT_SYMBOL_NS_GPL(iio_backend_data_size_set, IIO_BACKEND);
> +