linux-kernel - Re: [PATCH v2 2/2] i2c: Add GPIO-based hotplug gate

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Message-ID: <20230621103219.o2u33nsok7zngikf@intel.intel>
Date:   Wed, 21 Jun 2023 12:32:19 +0200
From:   Andi Shyti <andi.shyti@...nel.org>
To:     Svyatoslav Ryhel <clamor95@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Wolfram Sang <wsa@...nel.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] i2c: Add GPIO-based hotplug gate

Hi,

On Mon, Jun 19, 2023 at 06:37:32PM +0300, Svyatoslav Ryhel wrote:
> From: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> 
> Implement driver for hot-plugged I2C busses, where some devices on
> a bus are hot-pluggable and their presence is indicated by GPIO line.
> 
> Co-developed-by: Ion Agorria <ion@...rria.com>
> Signed-off-by: Ion Agorria <ion@...rria.com>
> Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> ---
>  drivers/i2c/Kconfig            |  11 ++
>  drivers/i2c/Makefile           |   1 +
>  drivers/i2c/i2c-hotplug-gpio.c | 266 +++++++++++++++++++++++++++++++++
>  3 files changed, 278 insertions(+)
>  create mode 100644 drivers/i2c/i2c-hotplug-gpio.c

without going through the code I am missing the big picture here.

What is this actually doing? Is this a new bus driver support? Is
this a feature to existing drivers? Is the GPIO an irq line for
signalling hoplugging and can be used by any driver or just this
one?

Without further discussing technicalities, can you please explain
better and more in detail what is the scope of this patch, why
there is a need for such a patch, how this new driver/feature
has been implemented and finally how it can be used.

This would help a lot so that I know already beforehand what I am
going to read without figuring it out.

Thanks,
Andi

PS Please notice that my set of questions is even longer than
your commit log :)