linux-kernel - Re: [PATCH 1/2] iio: adc: ad7124: Don't create more channels than the hardware is capable of

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Message-ID: <c94271b1-924b-4de6-b3bb-77e16265bb0d@baylibre.com>
Date: Fri, 8 Nov 2024 12:52:35 -0600
From: David Lechner <dlechner@...libre.com>
To: Uwe Kleine-König <u.kleine-koenig@...libre.com>,
 Lars-Peter Clausen <lars@...afoo.de>,
 Michael Hennerich <Michael.Hennerich@...log.com>,
 Jonathan Cameron <jic23@...nel.org>
Cc: Mircea Caprioru <mircea.caprioru@...log.com>, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] iio: adc: ad7124: Don't create more channels than the
 hardware is capable of

On 11/8/24 12:18 PM, Uwe Kleine-König wrote:
> The ad7124-4 and ad7124-8 both support 16 channel registers. Don't
> accept more (logical) channels from dt than that.

Why should the devicetree be limited by the number of channel
registers? Channel registers are a resource than can be
dynamically assigned, so it doesn't seem like the devicetree
should be specifying that assignment.

It's true we can't do a buffered read of more than 8 or 16
channels at the same time because it is limited by the number
of channel registers available on the chip.

But it seems reasonable that if there are more logical channels
than that, we could read 8 logical channels, then disable those
and enable a different 8 logical channels and read those by
reconfiguring the channel registers.