diff options
Diffstat (limited to 'drivers/usb/host/ehci-tegra.c')
| -rw-r--r-- | drivers/usb/host/ehci-tegra.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c index eb54df471d..e3620da15f 100644 --- a/drivers/usb/host/ehci-tegra.c +++ b/drivers/usb/host/ehci-tegra.c @@ -600,9 +600,18 @@ static int init_ulpi_usb_controller(struct fdt_usb *config, /* reset ULPI phy */ if (dm_gpio_is_valid(&config->phy_reset_gpio)) { - dm_gpio_set_value(&config->phy_reset_gpio, 0); - mdelay(5); + /* + * This GPIO is typically active-low, and marked as such in + * device tree. dm_gpio_set_value() takes this into account + * and inverts the value we pass here if required. In other + * words, this first call logically asserts the reset signal, + * which typically results in driving the physical GPIO low, + * and the second call logically de-asserts the reset signal, + * which typically results in driver the GPIO high. + */ dm_gpio_set_value(&config->phy_reset_gpio, 1); + mdelay(5); + dm_gpio_set_value(&config->phy_reset_gpio, 0); } /* Reset the usb controller */ |