On Mon, 3 Apr 2023 17:49:54 +0200 Paul Cercueil paul@crapouillou.net wrote:
Use the functions provided by the buffer-dma core to implement the DMABUF userspace API in the buffer-dmaengine IIO buffer implementation.
Since we want to be able to transfer an arbitrary number of bytes and not necesarily the full DMABUF, the associated scatterlist is converted to an array of DMA addresses + lengths, which is then passed to dmaengine_prep_slave_dma_array().
Signed-off-by: Paul Cercueil paul@crapouillou.net
A few things inline.
Thanks,
Jonathan
v3: Use the new dmaengine_prep_slave_dma_array(), and adapt the code to work with the new functions introduced in industrialio-buffer-dma.c.
.../buffer/industrialio-buffer-dmaengine.c | 69 ++++++++++++++++--- include/linux/iio/buffer-dma.h | 2 + 2 files changed, 60 insertions(+), 11 deletions(-)
diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c index 866c8b84bb24..faed9c2b089c 100644 --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c @@ -65,25 +65,68 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue, iio_buffer_to_dmaengine_buffer(&queue->buffer); struct dma_async_tx_descriptor *desc; enum dma_transfer_direction dma_dir;
- unsigned int i, nents, *lenghts;
- struct scatterlist *sgl;
- unsigned long flags;
- dma_addr_t *addrs; size_t max_size; dma_cookie_t cookie;
- size_t len_total;
- max_size = min(block->size, dmaengine_buffer->max_size);
- max_size = round_down(max_size, dmaengine_buffer->align);
- if (!block->bytes_used)
return -EINVAL;
- if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) {
block->bytes_used = max_size;
- if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) dma_dir = DMA_DEV_TO_MEM;
- } else {
- else dma_dir = DMA_MEM_TO_DEV;
- }
- if (!block->bytes_used || block->bytes_used > max_size)
return -EINVAL;
Ah this is dropping the code I moaned about earlier. I'll probably forget though so maybe add a note to that patch saying it goes away later anyway so I don't keep moaning about it in future versions.
- if (block->sg_table) {
sgl = block->sg_table->sgl;nents = sg_nents_for_len(sgl, block->bytes_used);addrs = kmalloc_array(nents, sizeof(*addrs), GFP_KERNEL);if (!addrs)return -ENOMEM;lenghts = kmalloc_array(nents, sizeof(*lenghts), GFP_KERNEL);
lengths?
if (!lenghts) {kfree(addrs);return -ENOMEM;}len_total = block->bytes_used;
- desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,
block->phys_addr, block->bytes_used, dma_dir,DMA_PREP_INTERRUPT);
for (i = 0; i < nents; i++) {addrs[i] = sg_dma_address(sgl);lenghts[i] = min(sg_dma_len(sgl), len_total);len_total -= lenghts[i];sgl = sg_next(sgl);}flags = block->cyclic ? DMA_PREP_REPEAT : DMA_PREP_INTERRUPT;desc = dmaengine_prep_slave_dma_array(dmaengine_buffer->chan,addrs, lenghts, nents,dma_dir, flags);kfree(addrs);kfree(lenghts);- } else {
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;if (block->bytes_used > max_size)return -EINVAL;desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,block->phys_addr,block->bytes_used, dma_dir,DMA_PREP_INTERRUPT);- }
diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h index e5e5817e99db..48f7ffaf0867 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -43,6 +43,7 @@ enum iio_block_state {
- @queue: Parent DMA buffer queue
- @kref: kref used to manage the lifetime of block
- @state: Current state of the block
- @cyclic: True if this is a cyclic buffer
- @fileio: True if this buffer is used for fileio mode
I might have commented on it earlier (I've lost track) but attach should be documented as well. Worth sanity checking by either building with W=1 or running kernel-doc over the files and fixing the warnings.
*/ struct iio_dma_buffer_block { @@ -67,6 +68,7 @@ struct iio_dma_buffer_block { */ enum iio_block_state state;
- bool cyclic; bool fileio;
struct dma_buf_attachment *attach;