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Date: Fri, 29 Apr 2016 10:45:14 +0200
Message-ID: <CACRpkdYY-5knOD0NwQjbQwAvhgRc_J5Pa1MWHw-P_7Wt29oEVQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/9] drivers: irqchip: Add STM32 external interrupts support
From: Linus Walleij <linus.walleij@linaro.org>
To: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Jason Cooper <jason@lakedaemon.net>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Mark Rutland <mark.rutland@arm.com>, Rob Herring <robh+dt@kernel.org>,
        "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Bruno Herrera <bruherrera@gmail.com>, Lee Jones <lee.jones@linaro.org>
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On Tue, Apr 19, 2016 at 10:00 AM, Maxime Coquelin
<mcoquelin.stm32@gmail.com> wrote:
> 2016-04-08 11:38 GMT+02:00 Linus Walleij <linus.walleij@linaro.org>:

>>         while ((stat = readl_relaxed(vic->base + VIC_IRQ_STATUS))) {
>>                 irq = ffs(stat) - 1;
>>                 handle_domain_irq(vic->domain, irq, regs);
>>                 handled = 1;
>>         }
>>
>>         return handled;
>> }
>
> Indeed, it would be better doing it like this.
> Do you think I could even do this with two nested loops to reduce the
> number of reg accesses?
> It would look like this (just compiled, not tested):
>
> static void stm32_irq_handler(struct irq_desc *desc)
> {
>     struct irq_domain *domain = irq_desc_get_handler_data(desc);
>     struct irq_chip_generic *gc = domain->gc->gc[0];
>     struct irq_chip *chip = irq_desc_get_chip(desc);
>     unsigned long pending;
>     int n;
>
>     chained_irq_enter(chip, desc);
>
>     while ((pending = irq_reg_readl(gc, EXTI_PR))) {
>         for_each_set_bit(n, &pending, BITS_PER_LONG) {
>             generic_handle_irq(irq_find_mapping(domain, n));
>         }
>     }

Looks clever! :)

If it also works, I'm in for it.

Yours,
Linus Walleij