linux-kernel - Re: [PATCH 2/2] iio: adc: mcp320x: add triggered buffer support

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Message-ID: <Yw8SJil96IT6fP0n@axis.com>
Date:   Wed, 31 Aug 2022 09:47:50 +0200
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     Jonathan Cameron <jic23@...nel.org>
CC:     kernel <kernel@...s.com>, "lars@...afoo.de" <lars@...afoo.de>,
        Axel Jonsson <Axel.Jonsson@...s.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] iio: adc: mcp320x: add triggered buffer support

On Sun, Aug 28, 2022 at 07:24:30PM +0200, Jonathan Cameron wrote:
> On Wed, 24 Aug 2022 12:40:02 +0200
> Vincent Whitchurch <vincent.whitchurch@...s.com> wrote:
> > Add support for triggered buffers.  Just read the channels in a loop to
> > keep things simple.
> 
> Just curious, but what other options are there?  A quick datasheet scroll
> through didn't seem to suggest you can overlap setup of next read with
> reading out the previous (common on SPI ADCs).

You're right that the hardware doesn't support any special method to
read out multiple channels; I can mention that in the commit message.
But I think you could construct a spi_message which a bunch of
spi_transfers which toggle the CS appropriately between them to read out
multiple channels in one go?  (Note that the variants have different
data formats, and many of the variants only have one channel.)