linux-kernel - Re: [PATCH v2 1/1] i2c: designware: set pinctrl recovery information from device pinctrl

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Date:   Thu, 15 Dec 2022 15:06:13 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     "Hawa, Hanna" <hhhawa@...zon.com>, Wolfram Sang <wsa@...nel.org>,
        jarkko.nikula@...ux.intel.com, mika.westerberg@...ux.intel.com,
        jsd@...ihalf.com, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, dwmw@...zon.co.uk, benh@...zon.com,
        ronenk@...zon.com, talel@...zon.com, jonnyc@...zon.com,
        hanochu@...zon.com, farbere@...zon.com, itamark@...zon.com
Subject: Re: [PATCH v2 1/1] i2c: designware: set pinctrl recovery information
 from device pinctrl

On Thu, Dec 15, 2022 at 11:28 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
> On Thu, Dec 15, 2022 at 10:15:35AM +0200, Hawa, Hanna wrote:
> > On 12/14/2022 6:09 PM, Andy Shevchenko wrote:
>
> ...
>
> > > > +     if (dev->dev->pins && dev->dev->pins->p)
> > > > +             rinfo->pinctrl = dev->dev->pins->p;
> > > Hmm... I don't see how this field is being used.
> > > Can you elaborate?
> >
> > This field is used in i2c_generic_scl_recovery(), if it's not NULL then the
> > flow will set the state to GPIO before running the recovery mechanism.
> >         if (bri->pinctrl)
> >                 pinctrl_select_state(bri->pinctrl, bri->pins_gpio);
>
> OK, but why that function doesn't use the dev->pins->p if it's defined?
> (As a fallback when rinfo->pinctrl is NULL.)

I don't understand the context of these things so can't say much
about it.

> > I saw that that the change failed in complication for SPARC architecture, as
> > the pins field is wraparound with CONFIG_PINCTRL in device struct. I though
> > on two options to solve the compilation error, first by adding wraparound of
> > CONFIG_PINCTRL when accessing the pins field. And the second option is to
> > add get function in pinctrl/devinfo.h file, which return the pins field, or
> > NULL in case the PINCTRL is not defined. Which option you think we can go
> > with?
>
> Getter with a stub sounds better to me, so you won't access some device core
> fields.
>
> Linus, what do you think about all these (including previous paragraph)?

A getter may be a good solution, it depends, it can also be pushed
somewhere local in the designware i2c driver can it not?
I am thinking that the rest of the code that is using that field is
certainly not going to work without pinctrl either.

Yours,
Linus Walleij