| Message ID | 1365106576-31816-4-git-send-email-jon-hunter@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@ti.com> > > Signed-off-by: Jon Hunter <jon-hunter@ti.com> looks alright: Reviewed-by: Felipe Balbi <balbi@ti.com> > --- > 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 >
On Thu, Apr 4, 2013 at 10:16 PM, Jon Hunter <jon-hunter@ti.com> 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@ti.com> > > Signed-off-by: Jon Hunter <jon-hunter@ti.com> Patch applied with Felipe's Reviewed-by tag. Thanks, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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
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@ti.com> Signed-off-by: Jon Hunter <jon-hunter@ti.com> --- drivers/gpio/gpio-omap.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)