Hi,
On 26-11-18 13:53, Andy Shevchenko wrote:
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"
Ok.
- 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
Ok.
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.
You're right an event with an IS_ERR(desc) is never added to the list of events, so this condition can never happen. I will add a follow up patch to v2 removing this unnecessary check.
I will prepare a v2 of this patch this evening or tomorrow.
Regards,
Hans