Messages in this thread | | | Date | Sun, 21 Nov 2021 17:52:48 +0000 | From | Paul Cercueil <> | Subject | Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues |
| |
Hi Lars,
Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen <lars@metafoo.de> a écrit : > On 11/15/21 3:19 PM, Paul Cercueil 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 these incoming and >> outgoing >> queues anyway, getting rid of them now makes the upcoming changes >> simpler. >> >> Signed-off-by: Paul Cercueil <paul@crapouillou.net> > The outgoing queue is going to be replaced by fences, but I think we > need to keep the incoming queue.
Blocks are always accessed in sequential order, so we now have a "queue->next_dequeue" that cycles between the buffers allocated for fileio.
>> [...] >> @@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable); >> static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue >> *queue, >> struct iio_dma_buffer_block *block) >> { >> - if (block->state == IIO_BLOCK_STATE_DEAD) { >> + if (block->state == IIO_BLOCK_STATE_DEAD) >> iio_buffer_block_put(block); >> - } else if (queue->active) { >> + else if (queue->active) >> iio_dma_buffer_submit_block(queue, block); >> - } else { >> + else >> block->state = IIO_BLOCK_STATE_QUEUED; >> - list_add_tail(&block->head, &queue->incoming); > If iio_dma_buffer_enqueue() is called with a dmabuf and the buffer is > not active, it will be marked as queued, but we don't actually keep a > reference to it anywhere. It will never be submitted to the DMA, and > it will never be signaled as completed.
We do keep a reference to the buffers, in the queue->fileio.blocks array. When the buffer is enabled, all the blocks in that array that are in the "queued" state will be submitted to the DMA.
Cheers, -Paul
| |