diff options
| author | Stephen Warren <swarren@nvidia.com> | 2016-09-15 12:19:37 -0600 |
|---|---|---|
| committer | Tom Warren <twarren@nvidia.com> | 2016-09-27 09:11:03 -0700 |
| commit | 2f6a7e8ce5df8b99d84bfd486c6f99d92322ce04 (patch) | |
| tree | eb77203c632945bc09e6991da1f4cbc37c782d9d /drivers | |
| parent | fc607d9ab96654973bd13dc0de1b2ff6d3d901b4 (diff) | |
ARM: tegra: fix USB ULPI PHY reset signal inversion confusion
USB ULPI PHY reset signals are typically active low. Consequently, they
should be marked as GPIO_ACTIVE_LOW in device tree, and indeed they are in
the Linux kernel DTs, and in DT properties that U-Boot doesn't yet use.
However, in DT properties that U-Boot does use, the value has been set to
0 (== GPIO_ACTIVE_HIGH) to work around a bug in U-Boot.
This change fixes the DT to correctly represent the HW, and fixes the
Tegra USB driver to cope with the fact that dm_gpio_set_value() internally
handles any inversions implied by the DT value GPIO_ACTIVE_LOW.
Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
Diffstat (limited to 'drivers')
| -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 */ |