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    SubjectRe: [RFC v2 0/5] gpio: add pinctrl based generic gpio driver
    Hi Andy,

    On Fri, Oct 20, 2023 at 12:27:58AM +0300, andy.shevchenko@gmail.com wrote:
    > Thu, Oct 05, 2023 at 11:58:38AM +0900, AKASHI Takahiro kirjoitti:
    > > This is a revised version of my previous RFC[1]. Although I modified
    > > the commits to make them look SCMI-independent, they are still posted
    > > as RFC because I have never tested them on real hardware.
    > >
    > > (background)
    > > I'm currently working on implementing SCMI pinctrl/gpio drivers
    > > on U-Boot[2]. Although the pinctrl driver for the kernel[3] was submitted
    > > by EPAM, it doesn't contain the gpio driver and I believe that we should
    > > discuss a couple of points on the kernel side to finalize my design for
    > > U-Boot.
    > >
    > > So this RFC is intended for reviews, especially to raise some issues.
    > >
    > > 1) how to obtain a value on an input pin
    > > All the existing gpio drivers are set to obtain a value on an input
    > > pin by accessing the hardware directly. In SCMI case, however, this is
    > > just impossible in its nature and must be supported via a protocol
    > > using "Input-value" configuration type. (See the spec[4], table-23.)
    > >
    > > The current pinconf framework is missing the feature (the pinconf
    > > parameter and a helper function). See patch#1, #2 and #3.
    > >
    > > Please note that there is an issue around the pin configuration in
    > > EPAM's current pinctrl driver as I commented[5].
    > >
    > > 2) DT bindings
    > > I would like to propose a generic binding for pinctrl based gpio driver.
    > > This allows a "consumer" driver to handle gpio pins like as other
    > > normal gpio controllers support. (patch#5)
    > >
    > > 3) generic GPIO driver
    > > Based on (2), I tried to prototype a generic driver in patch#4.
    > > Thanks to a set of existing pinctrl_gpio helper functions, except (1),
    > > It seems that the driver can be implemented not relying on pin controller
    > > specific code, at least for SCMI pinctrl.
    > >
    > > I will appreciate any comments.
    >
    > Any comment here: I'm listed as a designated reviewer of GPIO patches, why am I
    > not Cc'ed on this?

    My apologies. I will add you in Cc.

    > I definitely have some comments against the code (no DT,
    > though). Please, use (up-to-date) MAINTAINERS in your v3.

    Please don't hesitate to make comments here on v2 so that I can
    include your reviews in v3.

    Thanks,
    -Takahiro Akashi


    >
    > --
    > With Best Regards,
    > Andy Shevchenko
    >
    >

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