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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Mon, 18 Apr 2022 14:38:24 +0300
Message-ID: <CAHp75VfcxACmuw5pwPgSB9ud06hWtHCUrMifU1rZJ+h+dwG+bg@mail.gmail.com>
Subject: Re: [PATCH] gpio: use raw spinlock for gpio chip shadowed data
To:     Schspa Shi <schspa@gmail.com>
Cc:     "brgl@bgdev.pl" <brgl@bgdev.pl>,
        "f.fainelli@gmail.com" <f.fainelli@gmail.com>,
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On Mon, Apr 18, 2022 at 6:07 AM Schspa Shi <schspa@gmail.com> wrote:
> Andy Shevchenko <andy.shevchenko@gmail.com> writes:

...

> >   drivers/gpio/gpio-mmio.c    | 22 +++++++++++-----------
> >   include/linux/gpio/driver.h |  2 +-
> >
> > You can=E2=80=99t do it for one driver only. As I told it will require =
too much of additional churn to make this to be series.
> >
>
> It seems I have misunderstood your "too much of additional churn". Can
> you explain it?
> The gpio-mmio.c and driver.h here are the basics of other gpio
> drivers. In my opinion, these two files
> belong to the basic code of gpio, and functions such as bgpio_init are
> declared in
> include/linux/gpio/driver.h and implemented in
> drivers/gpio/gpio-mmio.c. So there is no churn.

When you change the member of the data structure, you have to change
all its users. You can't change only one at a time because it will be
a (compile-time) bisectability issue.

--=20
With Best Regards,
Andy Shevchenko