On Mon 27 Aug 09:56 PDT 2018, Lina Iyer wrote:

On Sun, Aug 26 2018 at 08:33 -0600, Linus Walleij wrote:

quoted

On Fri, Aug 17, 2018 at 6:39 PM Lina Iyer [off-list ref] wrote:

quoted

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 <redacted>
---
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.

quoted

+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)
+{

(...)

quoted

+       if (gpiochip_lock_as_irq(gc, irqd_to_hwirq(d))) {

(...)

quoted

+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.

Regards,
Bjorn