linux-kernel - Re: [PATCH v2 1/5] drivers: pinctrl: qcom: add wakeup capability to GPIO

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Message-ID: <20180828014652.GB13998@codeaurora.org>
Date:   Mon, 27 Aug 2018 19:46:52 -0600
From:   Lina Iyer <ilina@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Stephen Boyd <sboyd@...nel.org>, evgreen@...omium.org,
        rplsssn@...eaurora.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Andy Gross <andy.gross@...aro.org>,
        Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH v2 1/5] drivers: pinctrl: qcom: add wakeup capability to
 GPIO

On Mon, Aug 27 2018 at 18:26 -0600, Bjorn Andersson wrote:
>On Mon 27 Aug 09:56 PDT 2018, Lina Iyer wrote:
>
>> On Sun, Aug 26 2018 at 08:33 -0600, Linus Walleij wrote:
>> > On Fri, Aug 17, 2018 at 6:39 PM Lina Iyer <ilina@...eaurora.org> wrote:
>> >
>> > > QCOM SoC's that have Power Domain Controller (PDC) chip in the always-on
>> > > domain can wakeup the SoC, when interrupts and GPIOs are routed to the
>> > > its interrupt controller. Only select GPIOs that are deemed wakeup
>> > > capable are routed to specific PDC pins. During low power state, the
>> > > pinmux interrupt controller may be non-functional but the PDC would be.
>> > > The PDC can detect the wakeup GPIO is triggered and bring the TLMM to an
>> > > operational state.
>> > >
>> > > Interrupts that are level triggered will be detected at the TLMM when
>> > > the controller becomes operational. Edge interrupts however need to be
>> > > replayed again.
>> > >
>> > > Request the corresponding PDC IRQ, when the GPIO is requested as an IRQ,
>> > > but keep it disabled. During suspend, we can enable the PDC IRQ instead
>> > > of the GPIO IRQ, which may or not be detected.
>> > >
>> > > Signed-off-by: Lina Iyer <ilina@...eaurora.org>
>> > > ---
>> > > Changes in v1:
>> > >         - Trigger GPIO in h/w from PDC IRQ handler
>> > >         - Avoid big tables for GPIO-PDC map, pick from DT instead
>> > >         - Use handler_data
>> >
>> > Just for the record this is an impressive and much needed patch
>> > set, no other SoC developer has yet taken on the task of making this
>> > work so I very much appreciate that Qualcomm show the way.
>> >
>> > > +static int msm_gpio_pdc_pin_request(struct irq_data *d)
>> > > +static int msm_gpio_pdc_pin_release(struct irq_data *d)
>> > > +static int msm_gpio_irq_reqres(struct irq_data *d)
>> > > +{
>> > (...)
>> > > +       if (gpiochip_lock_as_irq(gc, irqd_to_hwirq(d))) {
>> > (...)
>> > > +static void msm_gpio_irq_relres(struct irq_data *d)
>> > > +{
>> > > +       gpiochip_unlock_as_irq(gc, irqd_to_hwirq(d));
>> > > +}
>> >
>> > FYI Hans Verkuil is working on a patch set that moves the
>> > lock/unlock as IRQ call to the irqchip request() and release()
>> > functions so we can switch a GPIO irqchip line from IRQ
>> > mode to say output at runtime without too much trouble.
>> > (CEC needs this.)
>> >
>> Thanks, I will look into Hans's RFCv2. But what would help me would be
>> to avoid creating the IRQ for the GPIO itself (I have the latent IRQ),
>> if I could just return that instead in gpio_to_irq(), it might be
>> easier. I understand ->to_irq() is supposed to be a translate function
>> only, I can avoid the dance of enabling and diabling the PDC IRQ on
>> suspend and resume.
>>
>
>I did implement gpio_to_irq() like this in the PMIC gpio/mpp drivers and
>we've since concluded that we need to move this to some hierarchical
>interrupt controller, because people like Linus expect to be able to say
>
>  interrupts = <&gpio_controller 1 IRQ_TYPE_EDGE_RISING>
>
>which is something used all over the place with the TLMM driver today.

Does it have to be &gpio_controller, can it be another interrupt controller?

Say,
	interrupts-extended = <&pdc 1 IRQ_TYPE_EDGE_RISING>;

-- Lina