From: Daniel Vetter <daniel@ffwll.ch>
To: Paul Cercueil <paul@crapouillou.net>
Cc: "Jonathan Cameron" <jic23@kernel.org>,
"Michael Hennerich" <Michael.Hennerich@analog.com>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org,
"Christian König" <christian.koenig@amd.com>,
linaro-mm-sig@lists.linaro.org,
"Alexandru Ardelean" <ardeleanalex@gmail.com>,
linux-media@vger.kernel.org
Subject: Re: [PATCH 00/15] iio: buffer-dma: write() and new DMABUF based API
Date: Mon, 15 Nov 2021 15:37:16 +0100 [thread overview]
Message-ID: <YZJwnPbgCOdeKq6S@phenom.ffwll.local> (raw)
In-Reply-To: <20211115141925.60164-1-paul@crapouillou.net>
On Mon, Nov 15, 2021 at 02:19:10PM +0000, Paul Cercueil wrote:
> Hi Jonathan,
>
> This patchset introduces a new userspace interface based on DMABUF
> objects, to complement the existing fileio based API.
>
> The advantage of this DMABUF based interface vs. the fileio
> interface, is that it avoids an extra copy of the data between the
> kernel and userspace. This is particularly userful for high-speed
> devices which produce several megabytes or even gigabytes of data per
> second.
>
> The first few patches [01/15] to [03/15] are not really related, but
> allow to reduce the size of the patches that introduce the new API.
>
> Patch [04/15] to [06/15] enables write() support to the buffer-dma
> implementation of the buffer API, to continue the work done by
> Mihail Chindris.
>
> Patches [07/15] to [12/15] introduce the new DMABUF based API.
>
> Patches [13/15] and [14/15] add support for cyclic buffers, only through
> the new API. A cyclic buffer will be repeated on the output until the
> buffer is disabled.
>
> Patch [15/15] adds documentation about the new API.
>
> For now, the API allows you to alloc DMABUF objects and mmap() them to
> read or write the samples. It does not yet allow to import DMABUFs
> parented to other subsystems, but that should eventually be possible
> once it's wired.
>
> This patchset is inspired by the "mmap interface" that was previously
> submitted by Alexandru Ardelean and Lars-Peter Clausen, so it would be
> great if I could get a review from you guys. Alexandru's commit was
> signed with his @analog.com address but he doesn't work at ADI anymore,
> so I believe I'll need him to sign with a new email.
Why dma-buf? dma-buf looks like something super generic and useful, until
you realize that there's a metric ton of gpu/accelerator bagage piled in.
So unless buffer sharing with a gpu/video/accel/whatever device is the
goal here, and it's just for a convenient way to get at buffer handles,
this doesn't sound like a good idea.
Also if the idea is to this with gpus/accelerators then I'd really like to
see the full thing, since most likely at that point you also want
dma_fence. And once we talk dma_fence things get truly horrible from a
locking pov :-( Or well, just highly constrained and I get to review what
iio is doing with these buffers to make sure it all fits.
Cheers, Daniel
>
> Cheers,
> -Paul
>
> Alexandru Ardelean (1):
> iio: buffer-dma: split iio_dma_buffer_fileio_free() function
>
> Paul Cercueil (14):
> iio: buffer-dma: Get rid of incoming/outgoing queues
> iio: buffer-dma: Remove unused iio_buffer_block struct
> iio: buffer-dma: Use round_down() instead of rounddown()
> iio: buffer-dma: Enable buffer write support
> iio: buffer-dmaengine: Support specifying buffer direction
> iio: buffer-dmaengine: Enable write support
> iio: core: Add new DMABUF interface infrastructure
> iio: buffer-dma: Use DMABUFs instead of custom solution
> iio: buffer-dma: Implement new DMABUF based userspace API
> iio: buffer-dma: Boost performance using write-combine cache setting
> iio: buffer-dmaengine: Support new DMABUF based userspace API
> iio: core: Add support for cyclic buffers
> iio: buffer-dmaengine: Add support for cyclic buffers
> Documentation: iio: Document high-speed DMABUF based API
>
> Documentation/driver-api/dma-buf.rst | 2 +
> Documentation/iio/dmabuf_api.rst | 94 +++
> Documentation/iio/index.rst | 2 +
> drivers/iio/adc/adi-axi-adc.c | 3 +-
> drivers/iio/buffer/industrialio-buffer-dma.c | 670 ++++++++++++++----
> .../buffer/industrialio-buffer-dmaengine.c | 42 +-
> drivers/iio/industrialio-buffer.c | 49 ++
> include/linux/iio/buffer-dma.h | 43 +-
> include/linux/iio/buffer-dmaengine.h | 5 +-
> include/linux/iio/buffer_impl.h | 8 +
> include/uapi/linux/iio/buffer.h | 30 +
> 11 files changed, 783 insertions(+), 165 deletions(-)
> create mode 100644 Documentation/iio/dmabuf_api.rst
>
> --
> 2.33.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
next prev parent reply other threads:[~2021-11-15 14:38 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
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 ` Daniel Vetter [this message]
2021-11-15 14:57 ` [PATCH 00/15] iio: buffer-dma: write() and new " 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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