Re: [PATCH v2 03/11] iio: buffer-dma: Enable buffer write support

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 5 Apr 2024 17:00:01 +0200
Nuno Sa <nuno.sa@analog.com> wrote:

> From: Paul Cercueil <paul@crapouillou.net>
> 
> Adding write support to the buffer-dma code is easy - the write()
> function basically needs to do the exact same thing as the read()
> function: dequeue a block, read or write the data, enqueue the block
> when entirely processed.
> 
> Therefore, the iio_buffer_dma_read() and the new iio_buffer_dma_write()
> now both call a function iio_buffer_dma_io(), which will perform this
> task.
> 
> Note that we preemptively reset block->bytes_used to the buffer's size
> in iio_dma_buffer_request_update(), as in the future the
> iio_dma_buffer_enqueue() function won't reset it.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>

One trivial comment on alignment that I noticed whilst reminding
myself of this patch. Otherwise looks good.


> +
> +/**
> + * iio_dma_buffer_read() - DMA buffer read callback
> + * @buffer: Buffer to read form
> + * @n: Number of bytes to read
> + * @user_buffer: Userspace buffer to copy the data to
> + *
> + * Should be used as the read callback for iio_buffer_access_ops
> + * struct for DMA buffers.
> + */
> +int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n,
> +	char __user *user_buffer)

Prefer aligning char with after the (

> +{
> +	return iio_dma_buffer_io(buffer, n, user_buffer, false);
> +}
>  EXPORT_SYMBOL_GPL(iio_dma_buffer_read);
>  
> +/**
> + * iio_dma_buffer_write() - DMA buffer write callback
> + * @buffer: Buffer to read form
> + * @n: Number of bytes to read
> + * @user_buffer: Userspace buffer to copy the data from
> + *
> + * Should be used as the write callback for iio_buffer_access_ops
> + * struct for DMA buffers.
> + */
> +int iio_dma_buffer_write(struct iio_buffer *buffer, size_t n,
> +			 const char __user *user_buffer)
> +{
> +	return iio_dma_buffer_io(buffer, n,
> +				 (__force __user char *)user_buffer, true);
> +}
> +EXPORT_SYMBOL_GPL(iio_dma_buffer_write);
>