From: David Lechner <dlechner@baylibre.com>
To: "Nuno Sá" <noname.nuno@gmail.com>, "Conor Dooley" <conor@kernel.org>
Cc: "Mark Brown" <broonie@kernel.org>,
"Jonathan Cameron" <jic23@kernel.org>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
"Conor Dooley" <conor+dt@kernel.org>,
"Nuno Sá" <nuno.sa@analog.com>,
"Michael Hennerich" <Michael.Hennerich@analog.com>,
"Lars-Peter Clausen" <lars@metafoo.de>,
"David Jander" <david@protonic.nl>,
"Martin Sperl" <kernel@martin.sperl.org>,
linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org
Subject: Re: [PATCH RFC v2 1/8] spi: dt-bindings: spi-peripheral-props: add spi-offloads property
Date: Thu, 30 May 2024 14:24:17 -0500 [thread overview]
Message-ID: <6db8ba66-841b-4425-9dd4-9d6e7b0463bf@baylibre.com> (raw)
In-Reply-To: <10991373cb9603803df63d8236c475807f6dde68.camel@gmail.com>
On 5/29/24 3:07 AM, Nuno Sá wrote:
> On Sun, 2024-05-26 at 18:35 +0100, Conor Dooley wrote:
>> It might be easy to do it this way right now, but be problematic for a
>> future device or if someone wants to chuck away the ADI provided RTL and
>> do their own thing for this device. Really it just makes me wonder if
>> what's needed to describe more complex data pipelines uses an of_graph,
>> just like how video pipelines are handled, rather than the implementation
>> of io-backends that don't really seem to model the flow of data.
>>
>
> Yeah, backends is more for devices/soft-cores that extend the functionality of the
> device they are connected too. Like having DACs/ADCs hdl cores for connecting to high
> speed controllers. Note that in some cases they also manipulate or even create data
> but since they fit in IIO, having things like the DMA property in the hdl binding was
> fairly straight.
>
> Maybe having an offload dedicated API (through spi) to get/share a DMA handle would
> be acceptable. Then we could add support to "import" it in the IIO core. Then it
> would be up to the controller to accept or not to share the handle (in some cases the
> controller could really want to have the control of the DMA transfers).
I could see this working for some SPI controllers, but for the AXI SPI Engine
+ DMA currently, the DMA has a fixed word size, so can't be used as a generic
DMA with arbitrary SPI xfers. For example, if the HDL is compiled with a 32-bit
word size, then even if we are reading 16-bit sample data, the DMA is going to
put it in a 32-bit slot. So one could argue that this is still doing some data
manipulation similar to the CRC checker example.
>
> Not familiar enough with of_graph so can't argue about it but likely is something
> worth looking at.
>
> - Nuno Sá
>>>
I did try implementing something using graph bindings when I first started
working on this, but it didn't seem to really give us any extra useful
information. It was just describing connections (endpoints) that I thought
we could just implicitly assume. After this discussion though, maybe worth
a second look. I'll have to think about it more.
next prev parent reply other threads:[~2024-05-30 19:24 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-11 0:44 [PATCH RFC v2 0/8] spi: axi-spi-engine: add offload support David Lechner
2024-05-11 0:44 ` [PATCH RFC v2 1/8] spi: dt-bindings: spi-peripheral-props: add spi-offloads property David Lechner
2024-05-13 16:46 ` Conor Dooley
2024-05-13 17:06 ` David Lechner
2024-05-14 18:46 ` Conor Dooley
2024-05-14 22:56 ` David Lechner
2024-05-16 21:32 ` Conor Dooley
2024-05-17 16:51 ` David Lechner
2024-05-19 12:53 ` Conor Dooley
2024-05-21 14:54 ` David Lechner
2024-05-22 18:24 ` Conor Dooley
2024-05-23 12:15 ` Nuno Sá
2024-05-23 12:45 ` Mark Brown
2024-05-23 14:31 ` Conor Dooley
2024-05-23 15:05 ` David Lechner
2024-05-26 15:42 ` Conor Dooley
2024-05-26 17:35 ` Conor Dooley
2024-05-29 8:07 ` Nuno Sá
2024-05-29 8:33 ` Conor Dooley
2024-05-30 19:18 ` Conor Dooley
2024-05-30 21:28 ` David Lechner
2024-05-31 12:47 ` Mark Brown
2024-05-31 7:39 ` Nuno Sá
2024-05-30 19:24 ` David Lechner [this message]
2024-05-31 7:33 ` Nuno Sá
2024-06-04 19:33 ` Conor Dooley
2024-06-04 19:39 ` David Lechner
2024-06-04 19:42 ` Conor Dooley
2024-06-04 20:04 ` David Lechner
2024-05-23 14:28 ` David Lechner
2024-05-23 14:57 ` Nuno Sá
2024-05-23 15:09 ` David Lechner
2024-05-23 15:30 ` Nuno Sá
2024-05-26 15:45 ` Conor Dooley
2024-05-29 20:10 ` David Lechner
2024-05-30 17:25 ` Conor Dooley
2024-05-30 18:42 ` Conor Dooley
2024-05-11 0:44 ` [PATCH RFC v2 2/8] spi: add basic support for SPI offloading David Lechner
2024-05-21 11:57 ` Nuno Sá
2024-05-11 0:44 ` [PATCH RFC v2 3/8] spi: add support for hardware triggered offload David Lechner
2024-05-11 16:51 ` Jonathan Cameron
2024-05-11 0:44 ` [PATCH RFC v2 4/8] spi: add offload xfer flags David Lechner
2024-05-11 0:44 ` [PATCH RFC v2 5/8] spi: dt-bindings: axi-spi-engine: document spi-offloads David Lechner
2024-05-11 0:44 ` [PATCH RFC v2 6/8] spi: axi-spi-engine: add offload support David Lechner
2024-05-21 12:31 ` Nuno Sá
2024-05-21 14:28 ` David Lechner
2024-05-22 12:08 ` Nuno Sá
2024-05-11 0:44 ` [PATCH RFC v2 7/8] dt-bindings: iio: adc: adi,ad7944: add SPI offload properties David Lechner
2024-05-11 0:44 ` [PATCH RFC v2 8/8] iio: adc: ad7944: add support for SPI offload David Lechner
2024-05-11 16:58 ` Jonathan Cameron
2024-05-11 18:41 ` David Lechner
2024-05-12 11:52 ` Jonathan Cameron
2024-05-13 15:15 ` David Lechner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6db8ba66-841b-4425-9dd4-9d6e7b0463bf@baylibre.com \
--to=dlechner@baylibre.com \
--cc=Michael.Hennerich@analog.com \
--cc=broonie@kernel.org \
--cc=conor+dt@kernel.org \
--cc=conor@kernel.org \
--cc=david@protonic.nl \
--cc=devicetree@vger.kernel.org \
--cc=jic23@kernel.org \
--cc=kernel@martin.sperl.org \
--cc=krzk+dt@kernel.org \
--cc=lars@metafoo.de \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-spi@vger.kernel.org \
--cc=noname.nuno@gmail.com \
--cc=nuno.sa@analog.com \
--cc=robh@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).