phy: tegra: xusb: Fix crash during pad power on/down

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2122414
Tested: Verify USB-A and USB-C are functional on Nvidia Orin board,
 and no regressions on other platforms.

commit 2a4ea83
Author: Jon Hunter <jonathanh@nvidia.com>
Date:   Mon Oct 10 14:51:32 2022 +0100

    phy: tegra: xusb: Fix crash during pad power on/down

    Commit a88520b ("usb: gadget: tegra: Reduce pad power") added calls
    to tegra_phy_xusb_utmi_pad_power_on/down in the Tegra XUDC driver to
    control the pad power. This change is causing a kernel panic when
    powering down the pads on entering suspend with the Jetson TX2 platform.
    The panic occurs because the 'xudc->curr_utmi_phy' is not configured on
    this platform and we do not check to see if the pointer is valid before
    attempting to deference the pointer. Fix this by checking to see if the
    'phy' pointer passed to tegra_phy_xusb_utmi_pad_power_on/down is valid.

    Fixes: a88520b ("usb: gadget: tegra: Reduce pad power")
    Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
    Link: https://lore.kernel.org/r/20221010135132.30809-1-jonathanh@nvidia.com
    Signed-off-by: Vinod Koul <vkoul@kernel.org>
    (cherry picked from commit 2a4ea83)

Signed-off-by: David Marlin <dmarlin@redhat.com>

Author: damarlin

drivers/phy/tegra/xusb.c

@@ -1461,8 +1461,14 @@ EXPORT_SYMBOL_GPL(tegra_phy_xusb_utmi_port_reset);
 
 void tegra_phy_xusb_utmi_pad_power_on(struct phy *phy)
 {
-	struct tegra_xusb_lane *lane = phy_get_drvdata(phy);
-	struct tegra_xusb_padctl *padctl = lane->pad->padctl;
+	struct tegra_xusb_lane *lane;
+	struct tegra_xusb_padctl *padctl;
+
+	if (!phy)
+		return;
+
+	lane = phy_get_drvdata(phy);
+	padctl = lane->pad->padctl;
 
 	if (padctl->soc->ops->utmi_pad_power_on)
 		padctl->soc->ops->utmi_pad_power_on(phy);
@@ -1471,8 +1477,14 @@ EXPORT_SYMBOL_GPL(tegra_phy_xusb_utmi_pad_power_on);
 
 void tegra_phy_xusb_utmi_pad_power_down(struct phy *phy)
 {
-	struct tegra_xusb_lane *lane = phy_get_drvdata(phy);
-	struct tegra_xusb_padctl *padctl = lane->pad->padctl;
+	struct tegra_xusb_lane *lane;
+	struct tegra_xusb_padctl *padctl;
+
+	if (!phy)
+		return;
+
+	lane = phy_get_drvdata(phy);
+	padctl = lane->pad->padctl;
 
 	if (padctl->soc->ops->utmi_pad_power_down)
 		padctl->soc->ops->utmi_pad_power_down(phy);