usb: dwc3: gadget: allow clock gating to work

The dwc3 core has internal clock gating support.

Let's allow that to happen by clearing the disable
bit in GCTL register.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 8d85023..fd1ac4d 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1164,6 +1164,14 @@
 	reg &= ~DWC3_GCTL_DISSCRAMBLE;
 	reg |= DWC3_GCTL_PRTCAPDIR(DWC3_GCTL_PRTCAP_DEVICE);
 
+	switch (DWC3_GHWPARAMS1_EN_PWROPT(dwc->hwparams.hwparams0)) {
+	case DWC3_GHWPARAMS1_EN_PWROPT_CLK:
+		reg &= ~DWC3_GCTL_DSBLCLKGTNG;
+		break;
+	default:
+		dev_dbg(dwc->dev, "No power optimization available\n");
+	}
+
 	/*
 	 * WORKAROUND: DWC3 revisions <1.90a have a bug
 	 * when The device fails to connect at SuperSpeed