Patch "usb: dwc2: drd: fix dwc2_drd_role_sw_set when clock could be disabled" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    usb: dwc2: drd: fix dwc2_drd_role_sw_set when clock could be disabled

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-dwc2-drd-fix-dwc2_drd_role_sw_set-when-clock-cou.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a1c85026dd4a741a4ec395e5aabed8f34fcc8ba8
Author: Amelie Delaunay <amelie.delaunay@xxxxxxxxxxx>
Date:   Tue Oct 5 11:53:04 2021 +0200

    usb: dwc2: drd: fix dwc2_drd_role_sw_set when clock could be disabled
    
    [ Upstream commit 8d387f61b0240854e81450c261beb775065bad5d ]
    
    In case of USB_DR_MODE_PERIPHERAL, the OTG clock is disabled at the end of
    the probe (it is not the case if USB_DR_MODE_HOST or USB_DR_MODE_OTG).
    The clock is then enabled on udc_start.
    If dwc2_drd_role_sw_set is called before udc_start (it is the case if the
    usb cable is plugged at boot), GOTGCTL and GUSBCFG registers cannot be
    read/written, so session cannot be overridden.
    To avoid this case, check the ll_hw_enabled value and enable the clock if
    it is available, and disable it after the override.
    
    Fixes: 17f934024e84 ("usb: dwc2: override PHY input signals with usb role switch support")
    Acked-by: Minas Harutyunyan <Minas.Harutyunyan@xxxxxxxxxxxx>
    Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20211005095305.66397-3-amelie.delaunay@xxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c
index 80eae88d76dda..99672360f34b0 100644
--- a/drivers/usb/dwc2/drd.c
+++ b/drivers/usb/dwc2/drd.c
@@ -7,6 +7,7 @@
  * Author(s): Amelie Delaunay <amelie.delaunay@xxxxxx>
  */
 
+#include <linux/clk.h>
 #include <linux/iopoll.h>
 #include <linux/platform_device.h>
 #include <linux/usb/role.h>
@@ -86,6 +87,20 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
 	}
 #endif
 
+	/*
+	 * In case of USB_DR_MODE_PERIPHERAL, clock is disabled at the end of
+	 * the probe and enabled on udc_start.
+	 * If role-switch set is called before the udc_start, we need to enable
+	 * the clock to read/write GOTGCTL and GUSBCFG registers to override
+	 * mode and sessions. It is the case if cable is plugged at boot.
+	 */
+	if (!hsotg->ll_hw_enabled && hsotg->clk) {
+		int ret = clk_prepare_enable(hsotg->clk);
+
+		if (ret)
+			return ret;
+	}
+
 	spin_lock_irqsave(&hsotg->lock, flags);
 
 	if (role == USB_ROLE_HOST) {
@@ -110,6 +125,9 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
 		/* This will raise a Connector ID Status Change Interrupt */
 		dwc2_force_mode(hsotg, role == USB_ROLE_HOST);
 
+	if (!hsotg->ll_hw_enabled && hsotg->clk)
+		clk_disable_unprepare(hsotg->clk);
+
 	dev_dbg(hsotg->dev, "%s-session valid\n",
 		role == USB_ROLE_NONE ? "No" :
 		role == USB_ROLE_HOST ? "A" : "B");