linux-kernel - Re: [PATCH] pinctrl: msm: Pass along set

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Message-ID: <20180712200432.GA887@codeaurora.org>
Date:   Thu, 12 Jul 2018 14:04:32 -0600
From:   Lina Iyer <ilina@...eaurora.org>
To:     Evan Green <evgreen@...omium.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, swboyd@...omium.org
Subject: Re: [PATCH] pinctrl: msm: Pass along set_wake failures

On Thu, Jul 12 2018 at 10:31 -0600, Evan Green wrote:
>On Tue, Jul 10, 2018 at 1:38 PM Lina Iyer <ilina@...eaurora.org> wrote:
>>
>> On Tue, Jul 10 2018 at 12:53 -0600, Evan Green wrote:
>> >On Mon, Jul 9, 2018 at 10:27 AM Bjorn Andersson
>> ><bjorn.andersson@...aro.org> wrote:
>> >Our understanding is the downstream kernel had an interrupt hierarchy
>> >of GIC > PDC > TLMM & everybody else. In the downstream world PDC
>> >acted transparently, forwarding most requests directly onto the GIC,
>> >but quietly handling wake interrupts as well. With the upstream PDC
>> >driver, the #interrupt-cells got changed to 2, and it seemed like
>> >folks didn't like the idea that PDC was acting transparently. Correct
>> >me if I'm wrong there. So now we're sort of unsure about how to wire
>> >in PDC. If we make everybody an interrupt child of PDC, then we lose
>> >the ability to specify the third GIC parameter, and we're stuck
>> >expressing interrupts with respect to PDC pins, which is an awkward
>> >mental translation.
>> Its an unfortunate side effect of the design. Drivers will have to
>> request the PDC pin for wakeup IRQs.
>
>Would they use the PDC pin to request their regular interrupt, and the
>PDC would turn around and ask the GIC for them, and also enable the
>wakeup interrupt?>
Yes, drivers would need to request a PDC pin since using the
interrupts-extended format and then enable that interrupt was a wakeup
interrupt.

> Or would devices have some sort of separate entry for wakeup
> interrupts?
Not sure how you mean. If it's the DT you are asking, then yes, they
would need to have a separate entry in DT.

	wake-device {
        	interrupts-extended = <&pdc 2 IRQ_TYPE_LEVEL_HIGH>;
	};

See Documentation/devicetree/bindings/interrupt-controller/qcom,pdc.txt

Thanks,
Lina