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From:   Haotien Hsu <haotienh@nvidia.com>
To:     Mathias Nyman <mathias.nyman@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        <linux-usb@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     Wayne Chang <waynec@nvidia.com>, JC Kuo <jckuo@nvidia.com>,
        WK Tsai <wtsai@nvidia.com>, Henry Lin <henryl@nvidia.com>,
        Haotien Hsu <haotienh@nvidia.com>
Subject: [PATCH v2] usb: xhci: tegra: Add shutdown callback for Tegra XUSB
Date:   Tue, 18 Jul 2023 17:14:25 +0800
Message-ID: <20230718091425.307589-1-haotienh@nvidia.com>
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From: Henry Lin <henryl@nvidia.com>

If memory accesses by the Tegra XUSB controller are translated through
the SMMU (System MMU), the hardware may continue accessing memory even
after the SMMU translations have been disabled during the shutdown
process and this can in turn cause unpredictable crashes.
Fix this by adding a shutdown implementation that ensures the hardware
is turned off during system reboot or shutdown.

Signed-off-by: Henry Lin <henryl@nvidia.com>
Signed-off-by: Haotien Hsu <haotienh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>

---
V1 -> V2: Resend for the typo in the mailing list
---
 drivers/usb/host/xhci-tegra.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index a56cc81b9404..6ef2eac9835d 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -1925,6 +1925,15 @@ static int tegra_xusb_probe(struct platform_device *pdev)
 	return err;
 }
 
+static void tegra_xusb_disable(struct tegra_xusb *tegra)
+{
+	tegra_xusb_powergate_partitions(tegra);
+	tegra_xusb_powerdomain_remove(tegra->dev, tegra);
+	tegra_xusb_phy_disable(tegra);
+	tegra_xusb_clk_disable(tegra);
+	regulator_bulk_disable(tegra->soc->num_supplies, tegra->supplies);
+}
+
 static int tegra_xusb_remove(struct platform_device *pdev)
 {
 	struct tegra_xusb *tegra = platform_get_drvdata(pdev);
@@ -1947,18 +1956,22 @@ static int tegra_xusb_remove(struct platform_device *pdev)
 
 	pm_runtime_put(&pdev->dev);
 
-	tegra_xusb_powergate_partitions(tegra);
-
-	tegra_xusb_powerdomain_remove(&pdev->dev, tegra);
-
-	tegra_xusb_phy_disable(tegra);
-	tegra_xusb_clk_disable(tegra);
-	regulator_bulk_disable(tegra->soc->num_supplies, tegra->supplies);
+	tegra_xusb_disable(tegra);
 	tegra_xusb_padctl_put(tegra->padctl);
 
 	return 0;
 }
 
+static void tegra_xusb_shutdown(struct platform_device *pdev)
+{
+	struct tegra_xusb *tegra = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(&pdev->dev);
+	disable_irq(tegra->xhci_irq);
+	xhci_shutdown(tegra->hcd);
+	tegra_xusb_disable(tegra);
+}
+
 static bool xhci_hub_ports_suspended(struct xhci_hub *hub)
 {
 	struct device *dev = hub->hcd->self.controller;
@@ -2666,6 +2679,7 @@ MODULE_DEVICE_TABLE(of, tegra_xusb_of_match);
 static struct platform_driver tegra_xusb_driver = {
 	.probe = tegra_xusb_probe,
 	.remove = tegra_xusb_remove,
+	.shutdown = tegra_xusb_shutdown,
 	.driver = {
 		.name = "tegra-xusb",
 		.pm = &tegra_xusb_pm_ops,
-- 
2.25.1