On Thu, Apr 04, 2013 at 03:16:14PM -0500, Jon Hunter wrote:
> The OMAP GPIO interrupt service routine is checking each bit in the
> GPIO interrupt status register to see which bits are set. It is not
> efficient to check every bit especially if only a few bits are set.
> Therefore, instead of checking every bit use the __ffs() function,
> which returns the location of the first set bit, to find all the set
> bits.
>
> This optimisation was suggested-by and developed in collaboration
> with Felipe Balbi.
>
> Cc: Felipe Balbi <balbi@xxxxxx>
>
> Signed-off-by: Jon Hunter <jon-hunter@xxxxxx>
looks alright:
Reviewed-by: Felipe Balbi <balbi@xxxxxx>
> ---
> drivers/gpio/gpio-omap.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index 5af7acd..685e850 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -689,7 +689,7 @@ static void gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
> {
> void __iomem *isr_reg = NULL;
> u32 isr;
> - unsigned int i;
> + unsigned int bit;
> struct gpio_bank *bank;
> int unmasked = 0;
> struct irq_chip *chip = irq_desc_get_chip(desc);
> @@ -730,9 +730,9 @@ static void gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
> if (!isr)
> break;
>
> - for (i = 0; isr != 0; isr >>= 1, i++) {
> - if (!(isr & 1))
> - continue;
> + while (isr) {
> + bit = __ffs(isr);
> + isr &= ~(1 << bit);
>
> /*
> * Some chips can't respond to both rising and falling
> @@ -741,10 +741,10 @@ static void gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
> * to respond to the IRQ for the opposite direction.
> * This will be indicated in the bank toggle_mask.
> */
> - if (bank->toggle_mask & (1 << i))
> - _toggle_gpio_edge_triggering(bank, i);
> + if (bank->toggle_mask & (1 << bit))
> + _toggle_gpio_edge_triggering(bank, bit);
>
> - generic_handle_irq(irq_find_mapping(bank->domain, i));
> + generic_handle_irq(irq_find_mapping(bank->domain, bit));
> }
> }
> /* if bank has any level sensitive GPIO pin interrupt
> --
> 1.7.10.4
>
--
balbi
Attachment:
signature.asc
Description: Digital signature
