Re: [RFC PATCH v4 07/10] gpio: Initial support for ROHM bd70528 GPIO block

[Matti Vaittinen]

On Mon, Feb 04, 2019 at 12:29:53PM +0100, Linus Walleij wrote:
> On Thu, Jan 31, 2019 at 1:08 PM Matti Vaittinen
> <matti.vaittinen@xxxxxxxxxxxxxxxxx> wrote:
> 
> > ROHM BD70528 PMIC has 4 GPIO pins. Allow them to be
> > controlled by GPIO framework.
> >
> > IRQs are handled by regmap-irq and GPIO driver is not
> > aware of the irq usage.
> >
> > Signed-off-by: Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>
> (...)
> > I dropped the review-by from Linus Walleij because I would like to
> > get a comment on if locking is required when we check the direction
> > in order to detect the correct register for getting the pin state.
> 
> I don't know that. You isn't regmap locking inherently?

This direction fetching and then the value reading are two separate
operations at regmap-level. I guess the regmap can't be holding any
locks during two indpendent operations.

> 
> > My initial feeling is that locking makes no sense.
> 
> Mine too.

Yep. I change the comment to explain why I think this race condition
is Ok. We can fix it if it ever turns out to be an issue.

> 
> > +       bdgpio->gpio.get_direction = &bd70528_get_direction;
> > +       bdgpio->gpio.direction_input = &bd70528_direction_input;
> > +       bdgpio->gpio.direction_output = &bd70528_direction_output;
> > +       bdgpio->gpio.set_config = &bd70528_gpio_set_config;
> > +       bdgpio->gpio.can_sleep = true;
> > +       bdgpio->gpio.get = &bd70528_gpio_get;
> > +       bdgpio->gpio.set = &bd70528_gpio_set;
> 
> Drop the &ampersand in from of the functions. All functions
> are pointers.

Yes they are. This & in front of functions when initializing a pointer
with their addresss is my old habit. I liked to consistently use & when
taking address of any beast, whether it was a variable or function.
Getting rid of old habits is not so easy :/ I'll clean thisi at v5 and
put back your Reviewed-by =) Thanks
> 
> With that:
> Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> 
> Yours,
> Linus Walleij

-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes.  Just then, he vanished ~~~