On 03/02/2013 05:48 AM, Felipe Balbi wrote:
> On Fri, Mar 01, 2013 at 11:22:47AM -0600, Jon Hunter wrote:
>> Currently the OMAP GPIO driver uses a legacy mapping for the GPIO IRQ
>> domain. This is not necessary because we do not need to assign a
>> specific interrupt number to the GPIO IRQ domain. Therefore, convert
>> the OMAP GPIO driver to use a linear mapping instead.
>>
>> Please note that this also allows to simplify the logic in the OMAP
>> gpio_irq_handler() routine, by using irq_find_mapping() to obtain the
>> virtual irq number from the GPIO bank and bank index.
>>
>> Reported-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
>> Signed-off-by: Jon Hunter <jon-hunter@xxxxxx>
>
> Reviewed-by: Felipe Balbi <balbi@xxxxxx>
>
> Just one suggestion below for a later patch.
>
>> @@ -680,7 +686,7 @@ static void gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
>> {
>> void __iomem *isr_reg = NULL;
>> u32 isr;
>> - unsigned int gpio_irq, gpio_index;
>> + unsigned int i;
>> struct gpio_bank *bank;
>> int unmasked = 0;
>> struct irq_chip *chip = irq_desc_get_chip(desc);
>> @@ -721,15 +727,10 @@ static void gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
>> if (!isr)
>> break;
>>
>> - gpio_irq = bank->irq_base;
>> - for (; isr != 0; isr >>= 1, gpio_irq++) {
>> - int gpio = irq_to_gpio(bank, gpio_irq);
>> -
>> + for (i = 0; isr != 0; isr >>= 1, i++) {
>> if (!(isr & 1))
>> continue;
>
> this will iterate over all 32 GPIOs, a better way to handle this would
> be to have something like:
Worse case, if only bit 31 was set then I agree this is not that
efficient. Or even if one bit is set. However, the loop itself will
iterate while isr != 0 so not always over each bit. No different to the
existing code.
> while (isr) {
> unsigned long bit = __ffs(isr);
>
> /* clear this bit */
> isr &= ~bit;
>
> generic_handle_irq(irq_find_mapping(bank->domain, bit);
> }
>
> this way you will only iterate the amount of bits enabled in the isr
> register.
Definitely cleaner but I am wondering which approach would be more
efficient from an instruction standpoint. This could definitely be much
more efficient if there is only a couple bits set.
> ps: completely untested ;-)
No problem. Thanks for the inputs.
Cheers
Jon
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