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Message-ID: <00c5f84a4bc5a4e3423f401af7b4f374c930407d.camel@gmail.com>
Subject: Re: [PATCH 12/13] iio: offload: add new PWM triggered DMA buffer
 driver
From: Nuno =?ISO-8859-1?Q?S=E1?= <noname.nuno@gmail.com>
To: David Lechner <dlechner@baylibre.com>, Mark Brown <broonie@kernel.org>, 
 Jonathan Cameron <jic23@kernel.org>, Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley
 <conor+dt@kernel.org>,  Michael Hennerich <michael.hennerich@analog.com>,
 Nuno =?ISO-8859-1?Q?S=E1?= <nuno.sa@analog.com>, Frank Rowand
 <frowand.list@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>, Uwe
 =?ISO-8859-1?Q?Kleine-K=F6nig?= <u.kleine-koenig@pengutronix.de>, Jonathan
 Corbet <corbet@lwn.net>,  linux-spi@vger.kernel.org,
 linux-iio@vger.kernel.org, devicetree@vger.kernel.org, 
 linux-doc@vger.kernel.org, linux-pwm@vger.kernel.org, 
 linux-kernel@vger.kernel.org
Date: Thu, 11 Jan 2024 10:31:15 +0100
In-Reply-To: <20240109-axi-spi-engine-series-3-v1-12-e42c6a986580@baylibre.com>
References: 
	<20240109-axi-spi-engine-series-3-v1-0-e42c6a986580@baylibre.com>
	 <20240109-axi-spi-engine-series-3-v1-12-e42c6a986580@baylibre.com>
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On Wed, 2024-01-10 at 13:49 -0600, David Lechner wrote:
> This adds a new driver for handling SPI offloading using a PWM as the
> trigger and DMA for the received data. This will be used by ADCs in
> conjunction with SPI controllers with offloading support to be able
> to sample at high rates without CPU intervention.
>=20
> Signed-off-by: David Lechner <dlechner@baylibre.com>
> ---
> =C2=A0drivers/iio/Kconfig=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 |=C2=A0=C2=
=A0 1 +
> =C2=A0drivers/iio/Makefile=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 |=C2=A0=C2=A0 =
1 +
> =C2=A0.../iio/buffer/industrialio-hw-triggered-buffer.c=C2=A0 |=C2=A0=C2=
=A0 1 +
> =C2=A0drivers/iio/offload/Kconfig=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0 |=C2=A0 21 ++
> =C2=A0drivers/iio/offload/Makefile=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0 |=C2=A0=C2=A0 2 +
> =C2=A0drivers/iio/offload/iio-pwm-triggered-dma-buffer.c | 212
> +++++++++++++++++++++
> =C2=A06 files changed, 238 insertions(+)
>=20
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 52eb46ef84c1..56738282d82f 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -90,6 +90,7 @@ source "drivers/iio/imu/Kconfig"
> =C2=A0source "drivers/iio/light/Kconfig"
> =C2=A0source "drivers/iio/magnetometer/Kconfig"
> =C2=A0source "drivers/iio/multiplexer/Kconfig"
> +source "drivers/iio/offload/Kconfig"

The offload stuff is something very particular to a spi controller feature.=
 Not
sure if having this as a generic thing makes sense at this point.

IMO, the IIO way of looking at the offload engine is as an HW triggered cor=
e for
capturing data. Hence, I would support the whole thing as an HW triggered
buffer. And, if we are really going the path of having the offload core as =
a
platform device, we could have different compatibles for each pair of trigg=
er +
data_capture (or explicit dt properties).

Just my 2 cents...

- Nuno S=C3=A1