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From: David Lechner <dlechner@baylibre.com>
To: nuno.sa@analog.com
Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-iio@vger.kernel.org,
	Olivier MOYSAN <olivier.moysan@foss.st.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Michael Hennerich <Michael.Hennerich@analog.com>
Subject: Re: [PATCH 10/12] iio: adc: ad9467: convert to backend framework
Date: Thu, 30 Nov 2023 18:12:12 -0600	[thread overview]
Message-ID: <CAMknhBEdXNkpEt-kXBez7zC0XGvo8AZ1G0Y9Y0XVr2EmpA_Qpw@mail.gmail.com> (raw)
In-Reply-To: <CAMknhBFbLju8UQJ7Uz85kHKrbK4mzt=wTRdnp40+PwWCJa5dsA@mail.gmail.com>

On Thu, Nov 30, 2023 at 5:30 PM David Lechner <dlechner@baylibre.com> wrote:
>
> On Tue, Nov 21, 2023 at 4:17 AM Nuno Sa via B4 Relay

<snip>

> > +       st->back = devm_iio_backend_get(&spi->dev, NULL);
>
> Based on the descriptions given of IIO frontend and backend, I was
> expecting this driver to be the backend since SPI is only used to
> configure the chip while the adi-axi-adc driver is the one determining
> the scan data format, providing the DMA (INDIO_BUFFER_HARDWARE), etc.
>
> Also, from a devicetree "describe the hardware" mindset, it doesn't
> seem like this chip (AD9467) should dictate a specific backend. I know
> it doesn't make sense practlically for this chip to not use DMA given
> the high sample rate, but why should the devicetree for this chip
> require it when there is nothing intrensic about this chip itself
> related to DMA?
>

Afterthought:

Put another way, it seems like it would be much easier to say "I, the
arbitrary frontend that actually handles the data from the LVDS
outputs, need a backend that provides a SPI connection to an AD9467
chip and takes care of turning on power supplies" than it is to say
"I, the AD9467 chip frontend, need an arbitrary backend that handles
reading data from the LVDS outputs in a very specific manner that is
determined by the driver, not the hardware".

  reply	other threads:[~2023-12-01  0:12 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-21 10:20 [PATCH 00/12] iio: add new backend framework Nuno Sa via B4 Relay
2023-11-21 10:20 ` Nuno Sa
2023-11-21 10:20 ` [PATCH 01/12] driver: core: allow modifying device_links flags Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-21 10:20 ` [PATCH 02/12] of: property: add device link support for io-backends Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-21 10:20 ` [PATCH 03/12] iio: add the IIO backend framework Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-12-04 15:38   ` Jonathan Cameron
2023-12-06 12:05     ` Nuno Sá
2023-12-06 17:15       ` Jonathan Cameron
2023-11-21 10:20 ` [PATCH 04/12] iio: adc: ad9467: fix reset gpio handling Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-30 21:41   ` David Lechner
2023-12-01  8:47     ` Nuno Sá
2023-12-01 17:01       ` David Lechner
2023-12-02  8:36         ` Nuno Sá
2023-12-04 15:15           ` Jonathan Cameron
2023-12-04 16:41             ` Nuno Sá
2023-11-21 10:20 ` [PATCH 05/12] iio: adc: ad9467: don't ignore error codes Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-30 21:44   ` David Lechner
2023-12-01  8:47     ` Nuno Sá
2023-12-04 15:19   ` Jonathan Cameron
2023-11-21 10:20 ` [PATCH 06/12] iio: adc: ad9467: add mutex to struct ad9467_state Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-30 21:50   ` David Lechner
2023-12-01  8:49     ` Nuno Sá
2023-12-04 15:21       ` Jonathan Cameron
2023-12-04 15:23   ` Jonathan Cameron
2023-12-04 16:10     ` Nuno Sá
2023-12-04 16:51       ` Jonathan Cameron
2023-11-21 10:20 ` [PATCH 07/12] iio: adc: ad9467: fix scale setting Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-21 10:20 ` [PATCH 08/12] iio: adc: ad9467: use spi_get_device_match_data() Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-21 10:20 ` [PATCH 09/12] iio: adc: ad9467: use chip_info variables instead of array Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-12-04 15:25   ` Jonathan Cameron
2023-12-04 16:24     ` Nuno Sá
2023-11-21 10:20 ` [PATCH 10/12] iio: adc: ad9467: convert to backend framework Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-22  0:54   ` kernel test robot
2023-11-30 23:30   ` David Lechner
2023-12-01  0:12     ` David Lechner [this message]
2023-12-01  9:08     ` Nuno Sá
2023-12-01 17:44       ` David Lechner
2023-12-02  8:46         ` Nuno Sá
2023-12-04  8:56           ` Nuno Sá
2023-12-04 15:48       ` Jonathan Cameron
2023-12-04 16:23         ` Nuno Sá
2023-12-04 16:57           ` Jonathan Cameron
2023-12-01  9:17     ` Nuno Sá
2023-11-21 10:20 ` [PATCH 11/12] iio: adc: adi-axi-adc: convert to regmap Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-12-04 15:51   ` Jonathan Cameron
2023-12-04 16:15     ` Nuno Sá
2023-11-21 10:20 ` [PATCH 12/12] iio: adc: adi-axi-adc: move to backend framework Nuno Sa via B4 Relay
2023-11-21 10:20   ` Nuno Sa
2023-11-21 23:27   ` kernel test robot
2023-11-25  7:42   ` kernel test robot
2023-11-30 23:33   ` David Lechner
2023-12-01  8:50     ` Nuno Sá
2023-11-23 17:36 ` [PATCH 00/12] iio: add new " Olivier MOYSAN
2023-11-24  9:15   ` Nuno Sá
2023-11-30 23:54 ` David Lechner
2023-12-01  8:41   ` Nuno Sá
2023-12-01  9:14     ` Nuno Sá
2023-12-02  3:53   ` David Lechner
2023-12-02  9:37     ` Nuno Sá
2023-12-02 16:16       ` David Lechner
2023-12-04 14:49         ` Jonathan Cameron

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