On Fri, Oct 31, 2014 at 10:39 AM, Dmitry Eremin-Solenikov <[email protected]> wrote: > 2014-10-31 10:48 GMT+03:00 Linus Walleij <[email protected]>: >> On Tue, Oct 28, 2014 at 1:01 AM, Dmitry Eremin-Solenikov >> <[email protected]> wrote: >> >>> Add gpiolib driver for gpio pins placed on the LoCoMo GA. >>> >>> Signed-off-by: Dmitry Eremin-Solenikov <[email protected]> >> > > [skipped] > >> (etc, everywhere this pattern occurs). >>> +static void locomo_gpio_set(struct gpio_chip *chip, >>> + unsigned offset, int value) >>> +{ >>> + struct locomo_gpio *lg = container_of(chip, struct locomo_gpio, >>> gpio); >>> + unsigned long flags; >>> + >>> + spin_lock_irqsave(&lg->lock, flags); >>> + >>> + __locomo_gpio_set(chip, offset, value); >>> + >>> + spin_unlock_irqrestore(&lg->lock, flags); >> >> If you actually always have to be getting and releasing a spin lock around >> the register writes, contemplate using regmap-mmio because that >> is part of what it does. >> >> But is this locking really necessary? > > I have a custom of doing such locking and never having to think about > somebody breaking into RMW cycles. > > Also isn't regmap an overkill here? Wouldn't regmap also do a lock/unlock > around each register read/write/RMW?
Yes that's the point: if you use regmap mmio you get the RMW-locking for free, with the regmap implementation. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
