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[v2,RESEND] usb: gadget: core: Fix ->udc_set_speed() speed handling

Message ID cbf14127-e788-0c51-4daa-2b25eec60b47@ti.com
State Accepted
Commit a4f0927ef588cf62bb864707261482c874352942
Headers show
Series [v2,RESEND] usb: gadget: core: Fix ->udc_set_speed() speed handling | expand

Commit Message

Roger Quadros Oct. 31, 2017, 1:56 p.m. UTC
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>

---
v2:
- Move speed limiting code to UDC core.

 drivers/usb/gadget/udc/core.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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Patch

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index d41d07a..def1b05 100644
--- 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);
+	}
 }
 
 /**