[PATCH v2 1/6] phy: tegra: xusb: Fix USB2 port regulator disable logic

[Diogo Ivo <diogo.ivo@tecnico.ulisboa.pt>]

The USB2 PHY mode handling on Tegra210 incorrectly relied on
regulator_is_enabled() when determining whether the VBUS supply should
be disabled during role changes. This is because regulator_is_enabled()
reports exactly what is states and not if there is an unbalanced number
of calls between regulator_enable() and regulator_disable(). For
example, regulator_is_enabled() always reports true on a fixed-regulator
with no enable gpio, which is the case on the Pixel C.

This then leads to the PHY driver wrongfully calling regulator_disable()
when transitioning from USB_ROLE_DEVICE to USB_ROLE_NONE since the driver
did not previously call the corresponding regulator_enable().

Fix this by keeping track of the current role and updating the logic to
disable the regulator only when the previous role was USB_ROLE_HOST.

Cc: stable@vger.kernel.org
Signed-off-by: Diogo Ivo <diogo.ivo@tecnico.ulisboa.pt>
---
v1->v2:
- Do not fix typo in comment
---
 drivers/phy/tegra/xusb-tegra210.c | 4 +++-
 drivers/phy/tegra/xusb.h          | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/phy/tegra/xusb-tegra210.c b/drivers/phy/tegra/xusb-tegra210.c
index 3409924498e9..3abdf0182d67 100644
--- a/drivers/phy/tegra/xusb-tegra210.c
+++ b/drivers/phy/tegra/xusb-tegra210.c
@@ -1936,12 +1936,14 @@ static int tegra210_usb2_phy_set_mode(struct phy *phy, enum phy_mode mode,
 			 * USB_ROLE_NONE from USB_ROLE_DEVICE, regulator is not
 			 * be enabled.
 			 */
-			if (regulator_is_enabled(port->supply))
+			if (port->role == USB_ROLE_HOST)
 				regulator_disable(port->supply);
 
 			tegra210_xusb_padctl_id_override(padctl, false);
 			tegra210_xusb_padctl_vbus_override(padctl, false);
 		}
+
+		port->role = submode;
 	}
 
 	mutex_unlock(&padctl->lock);
diff --git a/drivers/phy/tegra/xusb.h b/drivers/phy/tegra/xusb.h
index d2b5f9565132..273af147dfd3 100644
--- a/drivers/phy/tegra/xusb.h
+++ b/drivers/phy/tegra/xusb.h
@@ -317,6 +317,7 @@ struct tegra_xusb_usb2_port {
 	enum usb_dr_mode mode;
 	bool internal;
 	int usb3_port_fake;
+	enum usb_role role;
 };
 
 static inline struct tegra_xusb_usb2_port *

-- 
2.52.0