[PATCH] usb: dwc3: gadget: Fix .udc_set_speed()

[Roger Quadros]

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 or less than that
supported by the dwc3 controller driver.

Select the lesser of the 2 speeds so both are operating
within limits.

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

Fixes: 7d8d0639565f ("usb: dwc3: gadget: implement ->udc_set_speed()")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.13+
Reported-by: Dylan Howey <Dylan.Howey@xxxxxxxxxxxxx>
Signed-off-by: Roger Quadros <rogerq@xxxxxx>
---
 drivers/usb/dwc3/gadget.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index f064f15..9f27ec0 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2008,6 +2008,8 @@ static void dwc3_gadget_set_speed(struct usb_gadget *g,
 	unsigned long		flags;
 	u32			reg;
 
+	speed = min(g->max_speed, speed);
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
 	reg &= ~(DWC3_DCFG_SPEED_MASK);
-- 
cheers,
-roger

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