Mark Brown wrote at Thursday, August 04, 2011 6:02 PM:
On Thu, Aug 04, 2011 at 05:00:18PM -0600, Stephen Warren wrote:
- } else {
gpio = irq_to_gpio(irq);if (gpio_is_valid(gpio)) {ret = gpio_request(gpio, new->name);if (ret < 0)goto out_mask;ret = gpio_direction_input(gpio);if (ret < 0)goto out_mask;}If you treat failures as an error what happens when a driver is using a GPIO as both an interrupt and a GPIO? For example a driver which monitors the level on a GPIO and uses edge triggered IRQs to be notified of state changes.
Well, things break. This is essentially the problem I was describing in the PATCH 0 email, just with a slightly different motivation.
I suppose that an alternative here would be to simply ignore any errors from gpio_request. This might have the benefit of removing the need for the other two patches I posted in the series. However, it seems a little dirty; one benefit of the IRQ code calling gpio_request and honoring errors would be to detect when some completely unrelated code had a bug and had called gpio_request on the GPIO before. Such detection would be non-existent if we don't error out on gpio_request. Perhaps some mechanism is needed to indicate that the driver has explicitly already called gpio_request for a legitimate shared purpose, and only then ignore errors?
-- nvpublic