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Message-ID: <3fad2e61-c3e4-4bb1-bbea-101d5d0f91ee@baylibre.com>
Date: Thu, 23 May 2024 10:09:05 -0500
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Subject: Re: [PATCH RFC v2 1/8] spi: dt-bindings: spi-peripheral-props: add
 spi-offloads property
To: =?UTF-8?Q?Nuno_S=C3=A1?= <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>, =?UTF-8?Q?Nuno_S=C3=A1?=
 <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
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From: David Lechner <dlechner@baylibre.com>
In-Reply-To: <35de37c08331a8384aa9ebde3a9be5fec6fc418e.camel@gmail.com>
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On 5/23/24 9:57 AM, Nuno Sá wrote:
> On Thu, 2024-05-23 at 09:28 -0500, David Lechner wrote:
>> On 5/22/24 1:24 PM, Conor Dooley wrote:
>>> On Tue, May 21, 2024 at 09:54:39AM -0500, David Lechner wrote:
>>>> On Sun, May 19, 2024 at 7:53 AM Conor Dooley <conor@kernel.org> wrote:
>>>>>
>>>>> On Fri, May 17, 2024 at 11:51:58AM -0500, David Lechner wrote:
>>>>>> On Thu, May 16, 2024 at 4:32 PM Conor Dooley <conor@kernel.org> wrote:
>>>>>>> On Tue, May 14, 2024 at 05:56:47PM -0500, David Lechner wrote:
>>>>>
>>
> 
> ...
> 
>>
>> controller:
>> #spi-offload-cells = <2>: /* 1st cell = offload instance
>>                            * 2nd cell = trigger provider */
>>
> 
> What about things like DMA? I'm mentioning it a lot because it's way more complex
> having it on the controller (from a SW perspective). But from an HW point of view,
> it's always very similar (if not the same) as your case A.
> 

If we had a setup where there was more than one place that, e.g. the
RX stream from the offload could be piped, then I would add a 3rd
cell to describe that. If the hardware is fixed and the RX stream
always goes to a specific DMA channel, then it doesn't seem like we
need to describe that in the SPI controller node because the hardware
is fixed.