linux-kernel - Re: [PATCH v2 0/2] Add GPIO level-sensitive interrupt support

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Date:   Tue, 18 Feb 2020 19:10:12 +0100
From:   Alexandre Torgue <alexandre.torgue@...com>
To:     Marek Vasut <marex@...x.de>, Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        Linus Walleij <linus.walleij@...aro.org>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH v2 0/2] Add GPIO level-sensitive interrupt support

Hi Marek

On 2/18/20 5:25 PM, Marek Vasut wrote:
> On 2/18/20 2:12 PM, Alexandre Torgue wrote:
>> This series adds the possibility to handle gpio interrupts on level.
>>
>> GPIO hardware block is directly linked to EXTI block but EXTI handles
>> external interrupts only on edge. To be able to handle GPIO interrupt on
>> level a "hack" is done in gpio irq chip: parent interrupt (exti irq chip)
>> is retriggered following interrupt type and gpio line value.
>>
>> In exti irq chip, retrigger ops function is added.
> 
> btw. this might be unrelated, but is it possible to have e.g. gpioC2 set
> as trigger-level-low and gpioD2 set as trigger-edge-falling ? It seems
> 8eb2dfee9fb1 ("pinctrl: stm32: add lock mechanism for irqmux selection")
> prevents that.
> 

No it's not possible. Each gpio line doesn't have a dedicated Exti line 
Each Exti line is muxing between gpio banks.

Mapping is done as following:

EXTI0 = A0 or B0 or C0 .... or Z0 : selected by Mux
EXTI1 = A1 or B1 or C1 ....or Z1 : selected by Mux
EXTI2 = A2 or B2 or C2 ....or Z2 : selected by Mux
...

regards
Alexandre