On Sat, Jun 7, 2014 at 10:34 PM, Alexandre Courbot <[email protected]> wrote: > On Tue, Jun 3, 2014 at 12:29 AM, Rojhalat Ibrahim <[email protected]> wrote: >> Add a set_multiple function to the MPC8xxx GPIO chip driver and thereby allow >> for actual performance improvements when setting multiple outputs >> simultaneously. In my case the time needed to configure an FPGA goes down >> from >> 48 s to 20 s. >> >> Signed-off-by: Rojhalat Ibrahim <[email protected]> >> --- >> This patch depends on my previous patch "gpiolib: allow simultaneous setting >> of multiple GPIO outputs". >> >> Change log: >> v4: - change interface of the set_multiple driver function to use >> unsigned long as type for the bit fields >> - use generic bitops (which also use unsigned long for bit fields) >> v3: - change commit message >> v2: - add this patch (v1 included only changes to gpiolib) >> >> drivers/gpio/gpio-mpc8xxx.c | 27 +++++++++++++++++++++++++++ >> 1 file changed, 27 insertions(+) >> >> diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c >> index d7d6d72..d1ff879 100644 >> --- a/drivers/gpio/gpio-mpc8xxx.c >> +++ b/drivers/gpio/gpio-mpc8xxx.c >> @@ -105,6 +105,32 @@ static void mpc8xxx_gpio_set(struct gpio_chip *gc, >> unsigned int gpio, int val) >> spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags); >> } >> >> +static void mpc8xxx_gpio_set_multiple(struct gpio_chip *gc, >> + unsigned long *mask, unsigned long >> *bits) >> +{ >> + struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc); >> + struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm); >> + unsigned long flags; >> + int i; >> + >> + spin_lock_irqsave(&mpc8xxx_gc->lock, flags); >> + >> + for (i = 0; i < gc->ngpio; i++) { >> + if (*mask == 0) >> + break; > > Ok, so this works because presentely you can only have 32 GPIOs max on > this chip. But you cannot be sure that future revisions won't extend > that number ; and if this happens this function won't work as-is > anymore. I won't take much more code to make it more generic, so > please do it now to avoid hours of horrendous debugging to your future > self.
Looking at it twice you only have one data register, so there is probably not much you can do for the moment - please ignore my previous comment. Reviewed-by: Alexandre Courbot <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
