linux-kernel - Re: [PATCH v2 0/2] iio: ad74413r: allow setting sink current for digital input

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Date:   Sun, 12 Mar 2023 15:48:28 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Cosmin Tanislav <cosmin.tanislav@...log.com>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v2 0/2] iio: ad74413r: allow setting sink current for
 digital input

On Mon,  6 Mar 2023 10:42:59 +0100
Rasmus Villemoes <linux@...musvillemoes.dk> wrote:

> Depending on the actual hardware wired up to a digital input channel,
> it may be necessary to configure the ad74413r to sink a small
> current. For example, in the case of a simple mechanical switch, the
> charge on the external 68 nF capacitor (cf. the data sheet's Figure
> 34) will keep the channel as reading high even after the switch is
> turned off again.
> 
> Add a DT binding and driver support for setting the desired sink current.
> 
> I have chosen the term "drive strength" because it matches existing
> practice, even if this is only a sink. E.g. there's
> 
>  * @PIN_CONFIG_DRIVE_STRENGTH_UA: the pin will sink or source at most the current
>  *      passed as argument. The argument is in uA.
> 
> and indeed it would be trivial to hook up that
> PIN_CONFIG_DRIVE_STRENGTH_UA in ad74413r_gpio_set_comp_config().
> 
> However, unlike the debounce time, there does not appear to be any way
> to actually tweak the drive strength from userspace, nor do I know if
> that would actually be a good idea. For our application(s), the
> current sink needed is a property of the attached hardware, and thus
> can and should be defined in DT.
> 
> v2:
> - remove redundant type info in binding per Rob's bot
> - use min() instead of if() in ad74413r_set_comp_drive_strength() per Jonathan
> 
> Rasmus Villemoes (2):
>   dt-bindings: iio: ad74413r: allow setting sink current for digital
>     input
>   iio: ad74413r: wire up support for drive-strength-microamp property
> 
>  .../bindings/iio/addac/adi,ad74413r.yaml      |  9 ++++++++
>  drivers/iio/addac/ad74413r.c                  | 23 +++++++++++++++++++
>  2 files changed, 32 insertions(+)
> 
Series applied to the togreg branch of iio.git and pushed out as testing
for 0-day to take a first look at it.

Thanks,

Jonathan