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

[Lina Iyer]

On Sun, Aug 26 2018 at 08:33 -0600, Linus Walleij wrote:
> On Fri, Aug 17, 2018 at 6:39 PM Lina Iyer <ilina@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
> > ---
> > 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.

-- Lina

> I suspect that will make your work easier?
>
> Hans can you include Lina in the loop for your patches
> so she can take that into accoun because I think we might
> need that as a base for this.
>
> Yours,
> Linus Walleij