Some devices need an extra delay after losing VBUS, otherwise VBUS may
be detected as active at suspend time, preventing the PHY's suspension
by the VBUS detection sensor. This problem was found on Asus Transformer
TF700T (Tegra30) tablet device, where the USB PHY wakes up immediately
from suspend because VBUS sensor continues to detect VBUS as active after
disconnection. We need to poll the PHY's VBUS wakeup status until it's
deasserted before suspending PHY in order to fix this minor trouble.
Fixes: 35192007d28d ("usb: phy: tegra: Support waking up from a low power mode")
Reported-by: Maxim Schwalm <maxim.schwalm@xxxxxxxxx> # Asus TF700T
Tested-by: Maxim Schwalm <maxim.schwalm@xxxxxxxxx> # Asus TF700T
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
drivers/usb/phy/phy-tegra-usb.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
index fc5c6cab58ba..ff482c694200 100644
--- a/drivers/usb/phy/phy-tegra-usb.c
+++ b/drivers/usb/phy/phy-tegra-usb.c
@@ -64,6 +64,7 @@
#define A_VBUS_VLD_WAKEUP_EN BIT(30)
#define USB_PHY_VBUS_WAKEUP_ID 0x408
+#define VBUS_WAKEUP_STS BIT(10)
#define VBUS_WAKEUP_WAKEUP_EN BIT(30)
#define USB1_LEGACY_CTRL 0x410
@@ -645,6 +646,15 @@ static int utmi_phy_power_off(struct tegra_usb_phy *phy)
void __iomem *base = phy->regs;
u32 val;
+ /*
+ * Give hardware time to settle down after VBUS disconnection,
+ * otherwise PHY will immediately wake up from suspend.
+ */
+ if (phy->wakeup_enabled && phy->mode != USB_DR_MODE_HOST)
+ readl_relaxed_poll_timeout(base + USB_PHY_VBUS_WAKEUP_ID,
+ val, !(val & VBUS_WAKEUP_STS),
+ 5000, 100000);
+
utmi_phy_clk_disable(phy);
/* PHY won't resume if reset is asserted */
--
2.30.2
