usb: gadget: core: Fix ->udc_set_speed() speed handling

Currently UDC core calls ->udc_set_speed() with the speed parameter
containing the maximum speed supported by the gadget function
driver. This might very well be more than that supported by the
UDC controller driver.

Select the lesser of the 2 speeds so both UDC and gadget function
driver are operating within limits.

This fixes PHY Erratic errors and 2 second enumeration delay on
TI's AM437x platforms.

Fixes: 6099eca796ae ("usb: gadget: core: introduce ->udc_set_speed() method")
Cc: <stable@vger.kernel.org> # v4.13+
Reported-by: Dylan Howey <Dylan.Howey@tennantco.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 61422d624ad090f1dff586d59a9a31e2ce2ea0fb..93eff7dec2f5e9d7d9449b1189f8e5d2c91728e6 100644 (file)
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1069,8 +1069,12 @@ static inline void usb_gadget_udc_stop(struct usb_udc *udc)
 static inline void usb_gadget_udc_set_speed(struct usb_udc *udc,
                                            enum usb_device_speed speed)
 {
-       if (udc->gadget->ops->udc_set_speed)
-               udc->gadget->ops->udc_set_speed(udc->gadget, speed);
+       if (udc->gadget->ops->udc_set_speed) {
+               enum usb_device_speed s;
+
+               s = min(speed, udc->gadget->max_speed);
+               udc->gadget->ops->udc_set_speed(udc->gadget, s);
+       }
 }
 
 /**