On Mon, Nov 26, 2018 at 11:42:31AM +0100, Hans de Goede wrote:
> Commit 78d3a92edbfb ("gpiolib-acpi: Register GpioInt ACPI event handlers
> from a late_initcall") deferred the entire acpi_gpiochip_request_interrupt
> call for each event resource.
>
> This means it also delays the gpiochip_request_own_desc(..., "ACPI:Event")
> call. This is a problem if some AML code reads the GPIO pin before we
> run the deferred acpi_gpiochip_request_interrupt, because in that case
> acpi_gpio_adr_space_handler() will already have called
> gpiochip_request_own_desc(..., "ACPI:OpRegion") causing the call from
> acpi_gpiochip_request_interrupt to fail with -EBUSY and we will fail to
> register an event handler.
>
> acpi_gpio_adr_space_handler is prepared for acpi_gpiochip_request_interrupt
> already having claimed the pin, but the other way around does not work.
>
> One example of a problem this causes, is the event handler for the OTG
> ID pin on a Prowise PT301 tablet not registering, keeping the port stuck
> in whatever mode it was in during boot and e.g. only allowing charging
> after a reboot.
>
> This commit fixes this by only deferring the request_irq call and the
> initial run of edge-triggered IRQs instead of deferring all of
> acpi_gpiochip_request_interrupt.
Thanks for a patch with such nice description.
I have couple of nitpicks and one question below.
> * For gpiochips which call acpi_gpiochip_request_interrupts() before late_init
> - * (so builtin drivers) we register the ACPI GpioInt event handlers from a
> + * (so builtin drivers) we register the ACPI GpioInt irq-handlers from a
I would rather spell "IRQ handlers"
> * late_initcall_sync handler, so that other builtin drivers can register their
> * OpRegions before the event handlers can run. This list contains gpiochips
> - * for which the acpi_gpiochip_request_interrupts() has been deferred.
> + * for which the acpi_gpiochip_request_irqs() call has been deferred.
> mutex_unlock(&acpi_gpio_deferred_req_irqs_lock);
>
> - if (defer)
> - return;
> -
> - acpi_walk_resources(handle, "_AEI",
> - acpi_gpiochip_request_interrupt, acpi_gpio);
> + if (!defer)
> + acpi_gpiochip_request_irqs(acpi_gpio);
Can we leave above condition and put here just
acpi_gpiochip_request_irqs(acpi_gpio);
?
> list_for_each_entry_safe_reverse(event, ep, &acpi_gpio->events, node) {
> struct gpio_desc *desc;
>
> + if (event->irq_requested) {
> + if (event->irq_is_wake)
> + disable_irq_wake(event->irq);
> +
> + free_irq(event->irq, event);
> + }
>
> desc = event->desc;
> if (WARN_ON(IS_ERR(desc)))
I don't remember if I asked already about possible memory leak here.
Am I reading code right?
> continue;
Reading more code, I'm even not sure if this condition could ever happen.
--
With Best Regards,
Andy Shevchenko
