Re: [PATCH] gpiolib-acpi: Only defer request_irq for GpioInt ACPI event handlers

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Hi,

On 26-11-18 13:39, Mika Westerberg 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.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 78d3a92edbfb ("gpiolib-acpi: Register GpioInt ACPI event ...")
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
  drivers/gpio/gpiolib-acpi.c | 136 +++++++++++++++++++-----------------
  1 file changed, 73 insertions(+), 63 deletions(-)

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 55b72fbe1631..bda19373835a 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -22,8 +22,12 @@
  struct acpi_gpio_event {
  	struct list_head node;
  	acpi_handle handle;
+	irq_handler_t handler;
  	unsigned int pin;
  	unsigned int irq;
+	unsigned long irqflags;
+	bool irq_is_wake;
+	bool irq_requested;

It might be a good idea to add kernel-doc now for the struct since it
seems to be growing and it is not immediately clear what each field mean
anymore ;-)

Ok, will do for v2.

  	struct gpio_desc *desc;
  };
@@ -49,10 +53,10 @@ struct acpi_gpio_chip { /*
   * 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
   * 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.
   */
  static DEFINE_MUTEX(acpi_gpio_deferred_req_irqs_lock);
  static LIST_HEAD(acpi_gpio_deferred_req_irqs_list);
@@ -133,8 +137,43 @@ bool acpi_gpio_get_irq_resource(struct acpi_resource *ares,
  }
  EXPORT_SYMBOL_GPL(acpi_gpio_get_irq_resource);
-static acpi_status acpi_gpiochip_request_interrupt(struct acpi_resource *ares,
-						   void *context)
+static void acpi_gpiochip_request_irq(struct acpi_gpio_chip *acpi_gpio,
+				      struct acpi_gpio_event *event)
+{
+	int ret, value;
+
+	ret = request_threaded_irq(event->irq, NULL, event->handler,
+				   event->irqflags, "ACPI:Event", event);
+	if (ret) {
+		dev_err(acpi_gpio->chip->parent,
+			"Failed to setup interrupt handler for %d\n",
+			event->irq);
+		return;
+	}
+
+	if (event->irq_is_wake)
+		enable_irq_wake(event->irq);
+
+	event->irq_requested = true;
+
+	/* Make sure we trigger the initial state of edge-triggered IRQs */
+	value = gpiod_get_raw_value_cansleep(event->desc);
+	if (((event->irqflags & IRQF_TRIGGER_RISING) && value == 1) ||
+	    ((event->irqflags & IRQF_TRIGGER_FALLING) && value == 0))
+		event->handler(event->irq, event);
+}
+
+static void acpi_gpiochip_request_irqs(struct acpi_gpio_chip *acpi_gpio)
+{
+	struct acpi_gpio_event *event;
+
+	list_for_each_entry(event, &acpi_gpio->events, node)
+		acpi_gpiochip_request_irq(acpi_gpio, event);
+}
+
+static acpi_status
+acpi_gpiochip_request_interrupt_desc(struct acpi_resource *ares,
+				     void *context)

I wonder if there could be better name for this now that it does not
request anything? Maybe acpi_gpiochip_event_alloc() or similar?

Sure I will rename this to acpi_gpiochip_alloc_event (verb then subject
to follow the style of the rest of the file) for v2.

I will prepare a v2 of this patch this evening or tomorrow.

Regards,

Hans



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