On Mon, 3 Apr 2023 17:47:54 +0200
Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:
> Update the devm_iio_dmaengine_buffer_setup() function to support
> specifying the buffer direction.
>
> Update the iio_dmaengine_buffer_submit() function to handle input
> buffers as well as output buffers.
>
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> Reviewed-by: Alexandru Ardelean <ardeleanalex@xxxxxxxxx>
Just one trivial question inline.
Jonathan
> diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> index 5f85ba38e6f6..592d2aa9044c 100644
> --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> @@ -64,14 +64,25 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue,
> struct dmaengine_buffer *dmaengine_buffer =
> iio_buffer_to_dmaengine_buffer(&queue->buffer);
> struct dma_async_tx_descriptor *desc;
> + enum dma_transfer_direction dma_dir;
> + size_t max_size;
> dma_cookie_t cookie;
>
> - block->bytes_used = min(block->size, dmaengine_buffer->max_size);
> - block->bytes_used = round_down(block->bytes_used,
> - dmaengine_buffer->align);
> + max_size = min(block->size, dmaengine_buffer->max_size);
> + max_size = round_down(max_size, dmaengine_buffer->align);
> +
> + if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) {
> + block->bytes_used = max_size;
> + dma_dir = DMA_DEV_TO_MEM;
> + } else {
> + dma_dir = DMA_MEM_TO_DEV;
> + }
> +
> + if (!block->bytes_used || block->bytes_used > max_size)
> + return -EINVAL;
Two paths to here. Either DIRECTION_IN in which we just set things
up so conditions being checked are always fine (unless max_size == 0?
Can that happen?), or !DIRECTION_IN.
So why not move this into the else {} branch above?
>
> desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,
> - block->phys_addr, block->bytes_used, DMA_DEV_TO_MEM,
> + block->phys_addr, block->bytes_used, dma_dir,
> DMA_PREP_INTERRUPT);
> if (!desc)
> return -ENOMEM;
