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    Subject[PATCH 5.14 628/849] usb: dwc2: drd: fix dwc2_drd_role_sw_set when clock could be disabled
    Date
    From: Amelie Delaunay <amelie.delaunay@foss.st.com>

    [ 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@synopsys.com>
    Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
    Link: https://lore.kernel.org/r/20211005095305.66397-3-amelie.delaunay@foss.st.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/usb/dwc2/drd.c | 18 ++++++++++++++++++
    1 file changed, 18 insertions(+)

    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@st.com>
    */

    +#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");
    --
    2.33.0


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