From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: [PATCH] gpio / ACPI: Return -EPROBE_DEFER if the gpiochip was not found Date: Wed, 10 Jun 2015 16:05:05 +0300 Message-ID: <1433941505-135180-1-git-send-email-mika.westerberg@linux.intel.com> Return-path: Received: from mga01.intel.com ([192.55.52.88]:18176 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964781AbbFJNHK (ORCPT ); Wed, 10 Jun 2015 09:07:10 -0400 Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Linus Walleij Cc: Alexandre Courbot , "Rafael J. Wysocki" , Andy Shevchenko , Tobias Diedrich , Mika Westerberg , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org If a driver requests a GPIO described in its _CRS but the GPIO host controller (gpiochip) driver providing the GPIO has not been loaded yet acpi_get_gpiod() returns -ENODEV which causes the calling driver to fail. If the gpiochip driver is loaded afterwards the driver requesting the GPIO will not notice this. Better approach is to return -EPROBE_DEFER in such case. Then when the gpiochip driver appears the driver requesting the GPIO will be probed again. This also aligns ACPI GPIO lookup code closer to DT as it does pretty much the same when no gpiochip driver was found. Reported-by: Tobias Diedrich Signed-off-by: Mika Westerberg --- drivers/gpio/gpiolib-acpi.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c index 19b99d0c2bf0..b49006c81a7f 100644 --- a/drivers/gpio/gpiolib-acpi.c +++ b/drivers/gpio/gpiolib-acpi.c @@ -114,10 +114,11 @@ static inline int acpi_gpiochip_pin_to_gpio_offset(struct gpio_chip *chip, * @path: ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1") * @pin: ACPI GPIO pin number (0-based, controller-relative) * - * Returns GPIO descriptor to use with Linux generic GPIO API, or ERR_PTR - * error value + * Return: GPIO descriptor to use with Linux generic GPIO API, or ERR_PTR + * error value. Specifically returns %-EPROBE_DEFER if the referenced GPIO + * controller does not have gpiochip registered at the moment. This is to + * support probe deferral. */ - static struct gpio_desc *acpi_get_gpiod(char *path, int pin) { struct gpio_chip *chip; @@ -131,7 +132,7 @@ static struct gpio_desc *acpi_get_gpiod(char *path, int pin) chip = gpiochip_find(handle, acpi_gpiochip_find); if (!chip) - return ERR_PTR(-ENODEV); + return ERR_PTR(-EPROBE_DEFER); offset = acpi_gpiochip_pin_to_gpio_offset(chip, pin); if (offset < 0) -- 2.1.4