Re: [PATCH] gpio: use raw spinlock for gpio chip shadowed data

[Andy Shevchenko]

On Mon, Apr 18, 2022 at 6:07 AM Schspa Shi <schspa@xxxxxxxxx> wrote:
> Andy Shevchenko <andy.shevchenko@xxxxxxxxx> writes:

...

> >   drivers/gpio/gpio-mmio.c    | 22 +++++++++++-----------
> >   include/linux/gpio/driver.h |  2 +-
> >
> > You can’t 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.

-- 
With Best Regards,
Andy Shevchenko