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

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Thu, Apr 24, 2014 at 12:55 AM, Barry Song <21cnbao@xxxxxxxxx> 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.

Yours,
Linus Walleij
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