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Subject: Re: [PATCH v2 1/2] irqchip/stm32: Add irq retrigger support
To:     Marc Zyngier <maz@kernel.org>
CC:     Thomas Gleixner <tglx@linutronix.de>,
        Jason Cooper <jason@lakedaemon.net>,
        Linus Walleij <linus.walleij@linaro.org>, <marex@denx.de>,
        <linux-gpio@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>
References: <20200218131218.10789-1-alexandre.torgue@st.com>
 <20200218131218.10789-2-alexandre.torgue@st.com>
 <16d27f75-8157-7a92-ae61-b5b3ab05bdd9@st.com>
 <608d9c84813323ee3839f6ac21aa8f4e@kernel.org>
From:   Alexandre Torgue <alexandre.torgue@st.com>
Message-ID: <ae69e38a-78f9-ca68-c48c-86275e41b3bb@st.com>
Date:   Wed, 19 Feb 2020 14:07:22 +0100
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On 2/19/20 12:43 PM, Marc Zyngier wrote:
> On 2020-02-19 11:33, Alexandre Torgue wrote:
>> Fix Marc email address
>>
>> On 2/18/20 2:12 PM, Alexandre Torgue wrote:
>>> This commit introduces retrigger support for stm32_ext_h chip.
>>> It consists to rise the GIC interrupt mapped to an EXTI line.
>>>
>>> Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
>>>
>>> diff --git a/drivers/irqchip/irq-stm32-exti.c 
>>> b/drivers/irqchip/irq-stm32-exti.c
>>> index e00f2fa27f00..c971d115edb4 100644
>>> --- a/drivers/irqchip/irq-stm32-exti.c
>>> +++ b/drivers/irqchip/irq-stm32-exti.c
>>> @@ -604,12 +604,24 @@ static void stm32_exti_h_syscore_deinit(void)
>>>       unregister_syscore_ops(&stm32_exti_h_syscore_ops);
>>>   }
>>>   +static int stm32_exti_h_retrigger(struct irq_data *d)
>>> +{
>>> +    struct stm32_exti_chip_data *chip_data = 
>>> irq_data_get_irq_chip_data(d);
>>> +    const struct stm32_exti_bank *stm32_bank = chip_data->reg_bank;
>>> +    void __iomem *base = chip_data->host_data->base;
>>> +    u32 mask = BIT(d->hwirq % IRQS_PER_BANK);
>>> +
>>> +    writel_relaxed(mask, base + stm32_bank->swier_ofst);
>>> +
>>> +    return irq_chip_retrigger_hierarchy(d);
> 
> Calling irq_chip_retrigger_hierarchy here is really odd. If the write
> above has the effect of making the interrupt pending again, why do you
> need to force the retrigger any further?

To be honest, as we use hierarchical irq_chip, I thought it was the way 
to follow (to retrigger parent irq_chip). It makes maybe no sens here.
The most important to regenerate gic interrupt (associate to the exti 
line) is to write in SWIER register.

Alex

> 
>              M.