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

commit a4f0927ef588cf62bb864707261482c874352942 upstream.

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")
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index d41d07aae0cec07294cd9917d8ccdbd57f1f29ca..def1b05ffca0b103b99098365081ce4882f42d5d 100644 (file)
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1080,8 +1080,12 @@ 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);
+       }
 }
 
 /**