From 74379991f6eb760c8767a39c60b4a918af30f80b Mon Sep 17 00:00:00 2001 From: Fabio Estevam Date: Wed, 28 Jan 2015 13:19:17 -0200 Subject: [PATCH] usb: phy: phy-generic: Fix USB PHY gpio reset Since commit e9f2cefb0cdc2ae ("usb: phy: generic: migrate to gpio_desc") a kernel hang is observed on imx51-babbage board: [ 1.392824] ci_hdrc ci_hdrc.1: doesn't support gadget [ 1.397975] ci_hdrc ci_hdrc.1: EHCI Host Controller [ 1.403205] ci_hdrc ci_hdrc.1: new USB bus registered, assigned bus number 1 [ 1.422335] ci_hdrc ci_hdrc.1: USB 2.0 started, EHCI 1.00 [ 1.432962] hub 1-0:1.0: USB hub found [ 1.437119] hub 1-0:1.0: 1 port detected This hang happens because the reset GPIO stays at logic level 0. The USB PHY reset gpio is defined in the dts file as: reset-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>; , which means it is active low, so what the gpio reset pin needs to do in this case is the following: - Go to logic level 0 to reset the USB PHY - Stay at 0 for a bit - Go back to logic level 1 When switching to gpiod API we need to following according to Documentation/gpio/consumer.txt: "The first thing a driver must do with a GPIO is setting its direction. If no direction-setting flags have been given to gpiod_get*(), this is done by invoking one of the gpiod_direction_*() functions: int gpiod_direction_input(struct gpio_desc *desc) int gpiod_direction_output(struct gpio_desc *desc, int value)" Since no direction-setting flags have been given to devm_gpiod_get_optional() in our case, we need to use gpiod_direction_output to comply with the gpiod API. With this change the USB PHY reset performs a proper reset, the kernel boots fine and USB host is functional. Signed-off-by: Fabio Estevam Signed-off-by: Felipe Balbi --- drivers/usb/phy/phy-generic.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/usb/phy/phy-generic.c b/drivers/usb/phy/phy-generic.c index 48af0687bf11..70be50b734b2 100644 --- a/drivers/usb/phy/phy-generic.c +++ b/drivers/usb/phy/phy-generic.c @@ -64,11 +64,12 @@ static int nop_set_suspend(struct usb_phy *x, int suspend) static void nop_reset_set(struct usb_phy_generic *nop, int asserted) { - if (nop->gpiod_reset) - gpiod_set_value(nop->gpiod_reset, asserted); + if (!nop->gpiod_reset) + return; - if (!asserted) - usleep_range(10000, 20000); + gpiod_direction_output(nop->gpiod_reset, !asserted); + usleep_range(10000, 20000); + gpiod_set_value(nop->gpiod_reset, asserted); } /* interface to regulator framework */