From: Paul Cercueil <paul@crapouillou.net>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: "Jonathan Cameron" <jic23@kernel.org>,
"Alexandru Ardelean" <ardeleanalex@gmail.com>,
"Michael Hennerich" <Michael.Hennerich@analog.com>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues
Date: Sun, 21 Nov 2021 20:08:34 +0000 [thread overview]
Message-ID: <AMUX2R.XLGW1EZOMU9B2@crapouillou.net> (raw)
In-Reply-To: <332d001d-8b5a-bba2-c490-ed2e5efd0b1d@metafoo.de>
Le dim., nov. 21 2021 at 19:49:03 +0100, Lars-Peter Clausen
<lars@metafoo.de> a écrit :
> On 11/21/21 6:52 PM, Paul Cercueil wrote:
>> Hi Lars,
>>
>> Le dim., nov. 21 2021 at 17:23:35 +0100, Lars-Peter Clausen
>> \x7f<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 \x7f\x7fneed to keep the incoming queue.
>>
>> Blocks are always accessed in sequential order, so we now have a
>> \x7f"queue->next_dequeue" that cycles between the buffers allocated for
>> \x7ffileio.
>>
>>>> [...]
>>>> @@ -442,28 +435,33 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_disable);
>>>> static void iio_dma_buffer_enqueue(struct iio_dma_buffer_queue
>>>> \x7f\x7f\x7f*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 \x7f\x7fnot active, it will be marked as queued, but we don't actually
>>> keep a \x7f\x7freference to it anywhere. It will never be submitted to
>>> the DMA, and \x7f\x7fit will never be signaled as completed.
>>
>> We do keep a reference to the buffers, in the queue->fileio.blocks
>> \x7farray. When the buffer is enabled, all the blocks in that array
>> that \x7fare in the "queued" state will be submitted to the DMA.
>>
> But not when used in combination with the DMA buf changes later in
> this series.
>
That's still the case after the DMABUF changes of the series. Or can
you point me exactly what you think is broken?
-Paul
next prev parent reply other threads:[~2021-11-21 20:08 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-15 14:19 [PATCH 00/15] iio: buffer-dma: write() and new DMABUF based API Paul Cercueil
2021-11-15 14:19 ` [PATCH 01/15] iio: buffer-dma: Get rid of incoming/outgoing queues Paul Cercueil
2021-11-16 8:23 ` Alexandru Ardelean
2021-11-21 14:05 ` Jonathan Cameron
2021-11-21 16:23 ` Lars-Peter Clausen
2021-11-21 17:52 ` Paul Cercueil
2021-11-21 18:49 ` Lars-Peter Clausen
2021-11-21 20:08 ` Paul Cercueil [this message]
2021-11-22 15:08 ` Lars-Peter Clausen
2021-11-22 15:16 ` Paul Cercueil
2021-11-22 15:17 ` Lars-Peter Clausen
2021-11-22 15:27 ` Paul Cercueil
2021-11-15 14:19 ` [PATCH 02/15] iio: buffer-dma: Remove unused iio_buffer_block struct Paul Cercueil
2021-11-16 8:22 ` Alexandru Ardelean
2021-11-15 14:19 ` [PATCH 03/15] iio: buffer-dma: Use round_down() instead of rounddown() Paul Cercueil
2021-11-16 8:26 ` Alexandru Ardelean
2021-11-21 14:08 ` Jonathan Cameron
2021-11-22 10:00 ` Paul Cercueil
2021-11-27 15:15 ` Jonathan Cameron
2021-11-15 14:19 ` [PATCH 04/15] iio: buffer-dma: Enable buffer write support Paul Cercueil
2021-11-16 8:52 ` Alexandru Ardelean
2021-11-21 14:20 ` Jonathan Cameron
2021-11-21 17:19 ` Paul Cercueil
2021-11-27 15:17 ` Jonathan Cameron
2021-11-15 14:19 ` [PATCH 05/15] iio: buffer-dmaengine: Support specifying buffer direction Paul Cercueil
2021-11-16 8:53 ` Alexandru Ardelean
2021-11-15 14:19 ` [PATCH 06/15] iio: buffer-dmaengine: Enable write support Paul Cercueil
2021-11-16 8:55 ` Alexandru Ardelean
2021-11-15 14:19 ` [PATCH 07/15] iio: core: Add new DMABUF interface infrastructure Paul Cercueil
2021-11-21 14:31 ` Jonathan Cameron
2021-11-15 14:19 ` [PATCH 08/15] iio: buffer-dma: split iio_dma_buffer_fileio_free() function Paul Cercueil
2021-11-16 10:59 ` Alexandru Ardelean
2021-11-21 13:49 ` Jonathan Cameron
2021-11-15 14:19 ` [PATCH 09/15] iio: buffer-dma: Use DMABUFs instead of custom solution Paul Cercueil
2021-11-15 14:19 ` [PATCH 10/15] iio: buffer-dma: Implement new DMABUF based userspace API Paul Cercueil
2021-11-15 14:19 ` [PATCH 11/15] iio: buffer-dma: Boost performance using write-combine cache setting Paul Cercueil
2021-11-18 11:45 ` Paul Cercueil
2021-11-21 15:00 ` Jonathan Cameron
2021-11-21 17:43 ` Paul Cercueil
2021-11-25 17:29 ` Paul Cercueil
2021-11-27 16:05 ` Jonathan Cameron
2021-11-28 13:25 ` Lars-Peter Clausen
2021-11-27 15:20 ` Jonathan Cameron
2021-11-15 14:22 ` [PATCH 12/15] iio: buffer-dmaengine: Support new DMABUF based userspace API Paul Cercueil
2021-11-15 14:22 ` [PATCH 13/15] iio: core: Add support for cyclic buffers Paul Cercueil
2021-11-16 9:50 ` Alexandru Ardelean
2021-11-15 14:22 ` [PATCH 14/15] iio: buffer-dmaengine: " Paul Cercueil
2021-11-16 9:50 ` Alexandru Ardelean
2021-11-15 14:22 ` [PATCH 15/15] Documentation: iio: Document high-speed DMABUF based API Paul Cercueil
2021-11-21 15:10 ` Jonathan Cameron
2021-11-21 17:46 ` Paul Cercueil
2021-11-15 14:37 ` [PATCH 00/15] iio: buffer-dma: write() and new " Daniel Vetter
2021-11-15 14:57 ` Paul Cercueil
2021-11-16 16:02 ` Daniel Vetter
2021-11-16 16:31 ` Laurent Pinchart
2021-11-17 8:48 ` Christian König
2021-11-17 12:50 ` Paul Cercueil
2021-11-17 13:42 ` Hennerich, Michael
2021-11-21 13:57 ` Jonathan Cameron
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