linux-kernel - RE: [PATCH v7 3/5] usb: dwc2: add generic PHY framework support for dwc2 usb controler platform driver.

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Date:	Sat, 10 Jan 2015 23:51:57 +0000
From:	Paul Zimmerman <Paul.Zimmerman@...opsys.com>
To:	Yunzhi Li <lyz@...k-chips.com>,
	"Dinh Nguyen (dinguyen@...nsource.altera.com)" 
	<dinguyen@...nsource.altera.com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"heiko@...ech.de" <heiko@...ech.de>,
	"jwerner@...omium.org" <jwerner@...omium.org>,
	"dianders@...omium.org" <dianders@...omium.org>,
	"olof@...om.net" <olof@...om.net>,
	"huangtao@...k-chips.com" <huangtao@...k-chips.com>,
	"zyw@...k-chips.com" <zyw@...k-chips.com>,
	"cf@...k-chips.com" <cf@...k-chips.com>,
	"linux-rockchip@...ts.infradead.org" 
	<linux-rockchip@...ts.infradead.org>
Subject: RE: [PATCH v7 3/5] usb: dwc2: add generic PHY framework support for
 dwc2 usb controler platform driver.

> From: Yunzhi Li [mailto:lyz@...k-chips.com]
> Sent: Saturday, January 10, 2015 8:07 AM
> 
> 在 2015/1/9 10:15, Paul Zimmerman 写道:
> >> [...]
> >>   	/*
> >> -	 * Attempt to find a generic PHY, then look for an old style
> >> -	 * USB PHY, finally fall back to pdata
> >> +	 * If platform probe couldn't find a generic PHY or an old style
> >> +	 * USB PHY, fall back to pdata
> >>   	 */
> >> -	phy = devm_phy_get(dev, "usb2-phy");
> >> -	if (IS_ERR(phy)) {
> >> -		uphy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> >> -		if (IS_ERR(uphy)) {
> >> -			/* Fallback for pdata */
> >> -			plat = dev_get_platdata(dev);
> >> -			if (!plat) {
> >> -				dev_err(dev,
> >> -				"no platform data or transceiver defined\n");
> >> -				return -EPROBE_DEFER;
> >> -			}
> >> -			hsotg->plat = plat;
> >> -		} else
> >> -			hsotg->uphy = uphy;
> >> -	} else {
> >> -		hsotg->phy = phy;
> >> +	if (IS_ERR_OR_NULL(hsotg->phy) && IS_ERR_OR_NULL(hsotg->uphy)) {
> >> +		plat = dev_get_platdata(dev);
> >> +		if (!plat) {
> >> +			dev_err(dev,
> >> +			"no platform data or transceiver defined\n");
> >> +			return -EPROBE_DEFER;
> > Hi Yunzhi,
> >
> > Testing Felipe's testing/next branch on an Altera SOCFPGA platform,
> > the driver never loads because it always returns -EPROBE_DEFER here.
> > Apparently the SOCFPGA platform does not have any platform data
> > defined, because dev_get_platdata() always returns NULL.
> >
> > If I remove the -EPROBE_DEFER return and have it continue on, the
> > driver works. Reverting the patch also makes it work.
>      When I debug this problem, I checked socfpga.dtsi, there is a
> usbphy node defined for each
> dwc2 controller, so I think when running dwc2_driver_probe() uphy =
> devm_usb_get_phy()
> should get a valid usbphy pointer and hsotg->uphy will not be NULL or
> ERROR, then in dwc2_gadget_init()
> it will not return -EPROBE_DEFER. I have no idea about why you meet
> -EPROBE_DEFER, could you please tell
> me what's the return value of devm_usb_get_phy() on your socfpga board ?

I'm away from the hardware right now, but I just found this in a saved
boot log:

[    1.097268] usb_phy_generic soc:usbphy@0: Error requesting RESET GPIO
[    1.097285] usb_phy_generic: probe of soc:usbphy@0 failed with error -2

So that probably explains it. I'll dig into this some more on Monday.

-- 
Paul