diff mbox series

[v3,1/9] usb: phy: tegra: Add delay after power up

Message ID 20201218120246.7759-2-digetx@gmail.com (mailing list archive)
State Accepted
Commit b100402e93dcae0a88fe59d88d8114ce06d01f1e
Headers show
Series Support Runtime PM and host mode by Tegra ChipIdea USB driver | expand

Commit Message

Dmitry Osipenko Dec. 18, 2020, 12:02 p.m. UTC 
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>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/usb/phy/phy-tegra-usb.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
index 03a333797382..1296524e1bee 100644
--- 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;
 }