[PATCH 2/3] usb: dwc2: drd: fix dwc2_drd_role_sw_set when clock could be disabled
From: Amelie Delaunay <amelie.delaunay@foss.st.com>
Date: 2021-10-05 09:53:43
Also in:
lkml
Subsystem:
designware usb2 drd ip driver, the rest, usb subsystem · Maintainers:
Minas Harutyunyan, Linus Torvalds, Greg Kroah-Hartman
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@foss.st.com>
---
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@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");
--
2.25.1