linux-kernel - [PATCH v2] phy: tegra: xusb: reset VBUS & ID OVERRIDE

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Message-ID: <20250122105943.8057-1-henryl@nvidia.com>
Date: Wed, 22 Jan 2025 18:59:43 +0800
From: Henry Lin <henryl@...dia.com>
To: JC Kuo <jckuo@...dia.com>, Vinod Koul <vkoul@...nel.org>, "Kishon Vijay
 Abraham I" <kishon@...nel.org>, Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>, Henry Lin <henryl@...dia.com>
CC: <linux-phy@...ts.infradead.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, BH Hsieh <bhsieh@...dia.com>,
	<stable@...r.kernel.org>
Subject: [PATCH v2] phy: tegra: xusb: reset VBUS & ID OVERRIDE

From: BH Hsieh <bhsieh@...dia.com>

Observed VBUS_OVERRIDE & ID_OVERRIDE might be programmed
with unexpected value prior to XUSB PADCTL driver, this
could also occur in virtualization scenario.

For example, UEFI firmware programs ID_OVERRIDE=GROUNDED to set
a type-c port to host mode and keeps the value to kernel.
If the type-c port is connected a usb host, below errors can be
observed right after usb host mode driver gets probed. The errors
would keep until usb role class driver detects the type-c port
as device mode and notifies usb device mode driver to set both
ID_OVERRIDE and VBUS_OVERRIDE to correct value by XUSB PADCTL
driver.

[  173.765814] usb usb3-port2: Cannot enable. Maybe the USB cable is bad?
[  173.765837] usb usb3-port2: config error

Taking virtualization into account, asserting XUSB PADCTL
reset would break XUSB functions used by other guest OS,
hence only reset VBUS & ID OVERRIDE of the port in
utmi_phy_init.

Fixes: bbf711682cd5 ("phy: tegra: xusb: Add Tegra186 support")
Cc: stable@...r.kernel.org
Change-Id: Ic63058d4d49b4a1f8f9ab313196e20ad131cc591
Signed-off-by: BH Hsieh <bhsieh@...dia.com>
Signed-off-by: Henry Lin <henryl@...dia.com>
---
V1 -> V2: Only reset VBUS/ID OVERRIDE for otg/peripheral port

 drivers/phy/tegra/xusb-tegra186.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/phy/tegra/xusb-tegra186.c b/drivers/phy/tegra/xusb-tegra186.c
index 0f60d5d1c167..fae6242aa730 100644
--- a/drivers/phy/tegra/xusb-tegra186.c
+++ b/drivers/phy/tegra/xusb-tegra186.c
@@ -928,6 +928,7 @@ static int tegra186_utmi_phy_init(struct phy *phy)
 	unsigned int index = lane->index;
 	struct device *dev = padctl->dev;
 	int err;
+	u32 reg;

 	port = tegra_xusb_find_usb2_port(padctl, index);
 	if (!port) {
@@ -935,6 +936,16 @@ static int tegra186_utmi_phy_init(struct phy *phy)
 		return -ENODEV;
 	}

+	if (port->mode == USB_DR_MODE_OTG ||
+	    port->mode == USB_DR_MODE_PERIPHERAL) {
+		/* reset VBUS&ID OVERRIDE */
+		reg = padctl_readl(padctl, USB2_VBUS_ID);
+		reg &= ~VBUS_OVERRIDE;
+		reg &= ~ID_OVERRIDE(~0);
+		reg |= ID_OVERRIDE_FLOATING;
+		padctl_writel(padctl, reg, USB2_VBUS_ID);
+	}
+
 	if (port->supply && port->mode == USB_DR_MODE_HOST) {
 		err = regulator_enable(port->supply);
 		if (err) {
-- 
2.17.1