| Message ID | 20230403154800.215924-4-paul@crapouillou.net (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | iio: new DMABUF based API, v3 | expand |
On Mon, 3 Apr 2023 17:47:52 +0200 Paul Cercueil <paul@crapouillou.net> wrote: > The buffer-dma code was using two queues, incoming and outgoing, to > manage the state of the blocks in use. > > While this totally works, it adds some complexity to the code, > especially since the code only manages 2 blocks. It is much easier to > just check each block's state manually, and keep a counter for the next > block to dequeue. > > Since the new DMABUF based API wouldn't use the outgoing queue anyway, > getting rid of it now makes the upcoming changes simpler. > > With this change, the IIO_BLOCK_STATE_DEQUEUED is now useless, and can > be removed. > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> > > --- > v2: - Only remove the outgoing queue, and keep the incoming queue, as we > want the buffer to start streaming data as soon as it is enabled. > - Remove IIO_BLOCK_STATE_DEQUEUED, since it is now functionally the > same as IIO_BLOCK_STATE_DONE. I'm not that familiar with this code, but with my understanding this makes sense. I think it is independent of the earlier patches and is a useful change in it's own right. As such, does it make sense to pick this up ahead of the rest of the series? I'm assuming that discussion on the rest will take a while. No great rush as too late for the coming merge window anyway. Thanks, Jonathan
Hi Jonathan, Le dimanche 16 avril 2023 à 15:24 +0100, Jonathan Cameron a écrit : > On Mon, 3 Apr 2023 17:47:52 +0200 > Paul Cercueil <paul@crapouillou.net> wrote: > > > The buffer-dma code was using two queues, incoming and outgoing, to > > manage the state of the blocks in use. > > > > While this totally works, it adds some complexity to the code, > > especially since the code only manages 2 blocks. It is much easier > > to > > just check each block's state manually, and keep a counter for the > > next > > block to dequeue. > > > > Since the new DMABUF based API wouldn't use the outgoing queue > > anyway, > > getting rid of it now makes the upcoming changes simpler. > > > > With this change, the IIO_BLOCK_STATE_DEQUEUED is now useless, and > > can > > be removed. > > > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> > > > > --- > > v2: - Only remove the outgoing queue, and keep the incoming queue, > > as we > > want the buffer to start streaming data as soon as it is > > enabled. > > - Remove IIO_BLOCK_STATE_DEQUEUED, since it is now functionally > > the > > same as IIO_BLOCK_STATE_DONE. > > I'm not that familiar with this code, but with my understanding this > makes > sense. I think it is independent of the earlier patches and is a > useful > change in it's own right. As such, does it make sense to pick this > up > ahead of the rest of the series? I'm assuming that discussion on the > rest will take a while. No great rush as too late for the coming > merge > window anyway. Actually, you can pick patches 3 to 6 (when all have been acked). They add write support for buffer-dma implementations; which is a dependency for the rest of the patchset, but they can live on their own. Cheers, -Paul
On Tue, 18 Apr 2023 10:08:21 +0200 Paul Cercueil <paul@crapouillou.net> wrote: > Hi Jonathan, > > Le dimanche 16 avril 2023 à 15:24 +0100, Jonathan Cameron a écrit : > > On Mon, 3 Apr 2023 17:47:52 +0200 > > Paul Cercueil <paul@crapouillou.net> wrote: > > > > > The buffer-dma code was using two queues, incoming and outgoing, to > > > manage the state of the blocks in use. > > > > > > While this totally works, it adds some complexity to the code, > > > especially since the code only manages 2 blocks. It is much easier > > > to > > > just check each block's state manually, and keep a counter for the > > > next > > > block to dequeue. > > > > > > Since the new DMABUF based API wouldn't use the outgoing queue > > > anyway, > > > getting rid of it now makes the upcoming changes simpler. > > > > > > With this change, the IIO_BLOCK_STATE_DEQUEUED is now useless, and > > > can > > > be removed. > > > > > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> > > > > > > --- > > > v2: - Only remove the outgoing queue, and keep the incoming queue, > > > as we > > > want the buffer to start streaming data as soon as it is > > > enabled. > > > - Remove IIO_BLOCK_STATE_DEQUEUED, since it is now functionally > > > the > > > same as IIO_BLOCK_STATE_DONE. > > > > I'm not that familiar with this code, but with my understanding this > > makes > > sense. I think it is independent of the earlier patches and is a > > useful > > change in it's own right. As such, does it make sense to pick this > > up > > ahead of the rest of the series? I'm assuming that discussion on the > > rest will take a while. No great rush as too late for the coming > > merge > > window anyway. > > Actually, you can pick patches 3 to 6 (when all have been acked). They > add write support for buffer-dma implementations; which is a dependency > for the rest of the patchset, but they can live on their own. Remind me of that in the cover letter for v4. Thanks, Jonathan > > Cheers, > -Paul
diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index d348af8b9705..1fc91467d1aa 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -179,7 +179,7 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( } block->size = size; - block->state = IIO_BLOCK_STATE_DEQUEUED; + block->state = IIO_BLOCK_STATE_DONE; block->queue = queue; INIT_LIST_HEAD(&block->head); kref_init(&block->kref); @@ -191,16 +191,8 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block) { - struct iio_dma_buffer_queue *queue = block->queue; - - /* - * The buffer has already been freed by the application, just drop the - * reference. - */ - if (block->state != IIO_BLOCK_STATE_DEAD) { + if (block->state != IIO_BLOCK_STATE_DEAD) block->state = IIO_BLOCK_STATE_DONE; - list_add_tail(&block->head, &queue->outgoing); - } } /** @@ -261,7 +253,6 @@ static bool iio_dma_block_reusable(struct iio_dma_buffer_block *block) * not support abort and has not given back the block yet. */ switch (block->state) { - case IIO_BLOCK_STATE_DEQUEUED: case IIO_BLOCK_STATE_QUEUED: case IIO_BLOCK_STATE_DONE: return true; @@ -317,7 +308,6 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) * dead. This means we can reset the lists without having to fear * corrution. */ - INIT_LIST_HEAD(&queue->outgoing); spin_unlock_irq(&queue->list_lock); INIT_LIST_HEAD(&queue->incoming); @@ -456,14 +446,20 @@ static struct iio_dma_buffer_block *iio_dma_buffer_dequeue( struct iio_dma_buffer_queue *queue) { struct iio_dma_buffer_block *block; + unsigned int idx; spin_lock_irq(&queue->list_lock); - block = list_first_entry_or_null(&queue->outgoing, struct - iio_dma_buffer_block, head); - if (block != NULL) { - list_del(&block->head); - block->state = IIO_BLOCK_STATE_DEQUEUED; + + idx = queue->fileio.next_dequeue; + block = queue->fileio.blocks[idx]; + + if (block->state == IIO_BLOCK_STATE_DONE) { + idx = (idx + 1) % ARRAY_SIZE(queue->fileio.blocks); + queue->fileio.next_dequeue = idx; + } else { + block = NULL; } + spin_unlock_irq(&queue->list_lock); return block; @@ -539,6 +535,7 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf) struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buf); struct iio_dma_buffer_block *block; size_t data_available = 0; + unsigned int i; /* * For counting the available bytes we'll use the size of the block not @@ -552,8 +549,15 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf) data_available += queue->fileio.active_block->size; spin_lock_irq(&queue->list_lock); - list_for_each_entry(block, &queue->outgoing, head) - data_available += block->size; + + for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) { + block = queue->fileio.blocks[i]; + + if (block != queue->fileio.active_block + && block->state == IIO_BLOCK_STATE_DONE) + data_available += block->size; + } + spin_unlock_irq(&queue->list_lock); mutex_unlock(&queue->lock); @@ -617,7 +621,6 @@ int iio_dma_buffer_init(struct iio_dma_buffer_queue *queue, queue->ops = ops; INIT_LIST_HEAD(&queue->incoming); - INIT_LIST_HEAD(&queue->outgoing); mutex_init(&queue->lock); spin_lock_init(&queue->list_lock); @@ -645,7 +648,6 @@ void iio_dma_buffer_exit(struct iio_dma_buffer_queue *queue) continue; queue->fileio.blocks[i]->state = IIO_BLOCK_STATE_DEAD; } - INIT_LIST_HEAD(&queue->outgoing); spin_unlock_irq(&queue->list_lock); INIT_LIST_HEAD(&queue->incoming); diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h index 6564bdcdac66..18d3702fa95d 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -19,14 +19,12 @@ struct device; /** * enum iio_block_state - State of a struct iio_dma_buffer_block - * @IIO_BLOCK_STATE_DEQUEUED: Block is not queued * @IIO_BLOCK_STATE_QUEUED: Block is on the incoming queue * @IIO_BLOCK_STATE_ACTIVE: Block is currently being processed by the DMA * @IIO_BLOCK_STATE_DONE: Block is on the outgoing queue * @IIO_BLOCK_STATE_DEAD: Block has been marked as to be freed */ enum iio_block_state { - IIO_BLOCK_STATE_DEQUEUED, IIO_BLOCK_STATE_QUEUED, IIO_BLOCK_STATE_ACTIVE, IIO_BLOCK_STATE_DONE, @@ -73,12 +71,15 @@ struct iio_dma_buffer_block { * @active_block: Block being used in read() * @pos: Read offset in the active block * @block_size: Size of each block + * @next_dequeue: index of next block that will be dequeued */ struct iio_dma_buffer_queue_fileio { struct iio_dma_buffer_block *blocks[2]; struct iio_dma_buffer_block *active_block; size_t pos; size_t block_size; + + unsigned int next_dequeue; }; /** @@ -93,7 +94,6 @@ struct iio_dma_buffer_queue_fileio { * list and typically also a list of active blocks in the part that handles * the DMA controller * @incoming: List of buffers on the incoming queue - * @outgoing: List of buffers on the outgoing queue * @active: Whether the buffer is currently active * @fileio: FileIO state */ @@ -105,7 +105,6 @@ struct iio_dma_buffer_queue { struct mutex lock; spinlock_t list_lock; struct list_head incoming; - struct list_head outgoing; bool active;
The buffer-dma code was using two queues, incoming and outgoing, to manage the state of the blocks in use. While this totally works, it adds some complexity to the code, especially since the code only manages 2 blocks. It is much easier to just check each block's state manually, and keep a counter for the next block to dequeue. Since the new DMABUF based API wouldn't use the outgoing queue anyway, getting rid of it now makes the upcoming changes simpler. With this change, the IIO_BLOCK_STATE_DEQUEUED is now useless, and can be removed. Signed-off-by: Paul Cercueil <paul@crapouillou.net> --- v2: - Only remove the outgoing queue, and keep the incoming queue, as we want the buffer to start streaming data as soon as it is enabled. - Remove IIO_BLOCK_STATE_DEQUEUED, since it is now functionally the same as IIO_BLOCK_STATE_DONE. --- drivers/iio/buffer/industrialio-buffer-dma.c | 44 ++++++++++---------- include/linux/iio/buffer-dma.h | 7 ++-- 2 files changed, 26 insertions(+), 25 deletions(-)