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")
Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxxxxxxx>
---
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 80eae88d76dd..99672360f34b 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");
--
2.25.1
