Re: [PATCH] gpio: lynxpoint: lock IRQs when starting them

[Linus Walleij <linus.walleij@linaro.org>]

On Wed, Nov 20, 2013 at 7:29 PM, Grygorii Strashko
<grygorii.strashko@ti.com> wrote:
> On 11/20/2013 04:42 PM, Linus Walleij wrote:
>>
>> This uses the new API for tagging GPIO lines as in use by
>> IRQs. This enforces a few semantic checks on how the underlying
>> GPIO line is used.
(...)
>> +static unsigned int lp_irq_startup(struct irq_data *d)
>> +{
>> +     struct lp_gpio *lg = irq_data_get_irq_chip_data(d);
>> +
>> +     if (gpio_lock_as_irq(&lg->chip, irqd_to_hwirq(d)))
>> +             dev_err(lg->chip.dev,
>> +                     "unable to lock HW IRQ %lu for IRQ\n",
>> +                     irqd_to_hwirq(d));
>> +     return 0;
>> +}
>> +
>> +static void lp_irq_shutdown(struct irq_data *d)
>> +{
>> +     struct lp_gpio *lg = irq_data_get_irq_chip_data(d);
>> +
>> +     gpio_unlock_as_irq(&lg->chip, irqd_to_hwirq(d));
>> +}
>
> Seems, such changes may be risky, because .irq_startup()
> and irq_enable()/irq_umask() are mutually exclusive, at least at IRQ request time.
> request_threaded_irq()->__setup_irq()->irq_startup()
>
> More over, IRQ core assumes that IRQ is enabled, unmasked and ready for use after
> .irq_startup() call. You can check functions irq/chip.c->irq_startup() for more info.
>
> So, .irq_enable() functionality need to be duplicated in .irq_startup() at least.
>
> if you agree - above comment is valid for most of similar recent patches ;)

Yep. I just showcase what a worthless IRQ core user I am...

Now what would be the best way to call this?

Should I just move this into the .enable callback, and if there is no
such callback, create it and call the .unmask explicitly
at the end of it? It would seem a bit counter-intuitive to do this
in the .mask/.unmask callback, as that should only do exactly
that - mask/unmask.

I'll try this approach...

Yours,
Linus Walleij