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Commit e97bf632 authored by Jack Pham's avatar Jack Pham
Browse files

usb: dwc3_otg: Turn on VBUS before starting host 



Currently the VBUS regulator is enabled only after initializing
the xHCI host stack, which can result in enumeration failures
for certain devices. This is likely due to VBUS having a
finite rise time when it is turned on, especially when a load
is already attached. Mitigate this by enabling VBUS first before
starting the host stack.

CRs-Fixed: 599498
Change-Id: I9785ae4682d0a2dfbcec921b869fc03550e0db82
Signed-off-by: default avatarJack Pham <jackp@codeaurora.org>
parent 94c52e4c

drivers/usb/dwc3/dwc3_otg.c

+10 −8
Original line number Diff line number Diff line
@@ -180,6 +180,14 @@ static int dwc3_otg_start_host(struct usb_otg *otg, int on) 
	if (on) {

		dev_dbg(otg->phy->dev, "%s: turn on host\n", __func__);



		dwc3_otg_notify_host_mode(otg, on);

		ret = regulator_enable(dotg->vbus_otg);

		if (ret) {

			dev_err(otg->phy->dev, "unable to enable vbus_otg\n");

			dwc3_otg_notify_host_mode(otg, 0);

			return ret;

		}



		/*

		 * This should be revisited for more testing post-silicon.

		 * In worst case we may need to disconnect the root hub
@@ -205,19 +213,13 @@ static int dwc3_otg_start_host(struct usb_otg *otg, int on) 
			dev_err(otg->phy->dev,

				"%s: failed to add XHCI pdev ret=%d\n",

				__func__, ret);

			regulator_disable(dotg->vbus_otg);

			dwc3_otg_notify_host_mode(otg, 0);

			return ret;

		}



		hcd = platform_get_drvdata(dwc->xhci);

		dwc3_otg_set_host(otg, &hcd->self);

		dwc3_otg_notify_host_mode(otg, on);



		ret = regulator_enable(dotg->vbus_otg);

		if (ret) {

			dev_err(otg->phy->dev, "unable to enable vbus_otg\n");

			platform_device_del(dwc->xhci);

			return ret;

		}



		/* re-init OTG EVTEN register as XHCI reset clears it */

		if (ext_xceiv && !ext_xceiv->otg_capability)