[PATCH 3/4] gpio: make handler_data configurable while using gpiolib_irqchip

[Barry Song]

2014-04-24 7:09 GMT+08:00 Linus Walleij <linus.walleij at linaro.org>:
> On Thu, Apr 24, 2014 at 12:55 AM, Barry Song <21cnbao at gmail.com> wrote:
>
>>> NAK, the whole idea with the function gpiochip_set_chained_irqchip()
>>> is that its sets things up so that the gpiochip is passed as handler
>>> data on the parent IRQ, akin to how the gpiochip is passed as
>>> chip data on the cascaded IRQs.
>>
>> i think it is a really bad idea as the parent handler might not want
>> the whole chip if the chip has several parents and each parent want a
>> separate handler_data.
>> this patch doesn't break your way as the parameter is void *, drivers
>> which use your way don't need any change. but for drivers which want
>> more special handler_data, it supports better.
>
> This is perfectly possible, just don't use
> gpiochip_set_chained_irqchip() which has this semantic
> effect.
>
> Use irq_set_chained_handler() and irq_set_handler_data()
> directly instead.
>
> I do see that this is maybe easier for the handler to get the bank
> passed in.
>
> However when I in the RFT patches change the driver to allocate
> and pass a struct for the gpio chip, it all looks a bit different.
> You would have to get the sgpio from the bank instead, which
> may require to introduce a special pointer for that.
>
> What we want to get rid of is this:
>
> for (i = 0; i < SIRFSOC_GPIO_BANK_SIZE; i++) {
>                 bank = &sgpio->sgpio_bank[i];
>                 if (bank->parent_irq == irq)
>                         break;
> }
> BUG_ON (i == SIRFSOC_GPIO_BANK_SIZE);
>
> So what about passing something like that to the handler:
>
> struct sirf_irq_handler_data {
>     struct sirfsoc_gpio_chip *sgpio;
>     struct sirfsoc_gpio_bank *bank;
> };
>
> Then the irq handler instantly have pointers to all it needs.
> But maybe it's better to just pass the bank, whatdoIknow.

only if we move to irq_set_chained_handler() and
irq_set_handler_data() directly and set bank-specific handler_data
manually, it works.
my point is that will we make the gpiochip_set_chained_irqchip() more
general for this kind of cases too since you have had a good API to
wrap things?

>
> Yours,
> Linus Walleij

-barry