usb: phy: tegra: Add delay after power up

The PHY hardware needs the delay of 2ms after power up, otherwise initial
interrupt may be lost if USB controller is accessed before PHY is settled
down. Previously this issue was masked by implicit delays, but now it pops
up after squashing the older ehci-tegra driver into the ChipIdea driver.

Tested-by: Matt Merhar <mattmerhar@protonmail.com>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Ion Agorria <ion@agorria.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20201218120246.7759-2-digetx@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
index 03a333797382f3c7c74c7dab196e84c026b8569f..1296524e1beec0c0492d36a62ea0d69a1d411bab 100644 (file)
--- a/drivers/usb/phy/phy-tegra-usb.c
+++ b/drivers/usb/phy/phy-tegra-usb.c
@@ -784,6 +784,9 @@ static int tegra_usb_phy_power_on(struct tegra_usb_phy *phy)
 
        phy->powered_on = true;
 
+       /* Let PHY settle down */
+       usleep_range(2000, 2500);
+
        return 0;
 }