Re: [PATCH v2 3/5] usb: dwc2: Add generic PHY framework support for dwc2 usb controler platform driver.

[Yunzhi Li]

Hi Paul:

Thank you for replying.

On 2014/12/6 3:04, Paul Zimmerman wrote:
> > From: Yunzhi Li [mailto:lyz@xxxxxxxxxxxxxx]
> > Sent: Friday, December 05, 2014 4:52 AM
> >
> > Get PHY parameters from devicetree and power off usb PHY during
> > system suspend.
> >
> > Signed-off-by: Yunzhi Li <lyz@xxxxxxxxxxxxxx>
> > ---
> >
> >   drivers/usb/dwc2/gadget.c   | 33 ++++++++++++---------------------
> >   drivers/usb/dwc2/platform.c | 34 ++++++++++++++++++++++++++++++++++
> >   2 files changed, 46 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> > index 200168e..2601c61 100644
> > --- a/drivers/usb/dwc2/gadget.c
> > +++ b/drivers/usb/dwc2/gadget.c
> > [...]
> >
> >   	/*
> > -	 * 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;
> > +		}
> > +		hsotg->plat = plat;
> > +	} else if (hsotg->phy) {
> You have changed the behavior here. Previously, the driver would work
> even if there were no phys or pdata defined. Now it will return
> -EPROBE_DEFER instead. Are you sure that won't break any existing
> platforms?
I don't really catch your meaning. Could you please point out where is 
the difference? Thanks .

In previous version, if there were no phy or usb_phy defined, 
devm_phy_get() and devm_usb_get_phy() both failed, then driver falls 
back to find pdata, if no pdata defined dev_get_platdata() returns NULL, 
then dwc2_gadget_init returns -EPROBE_DEFER and the dwc2_driver_probe 
fail. So I think, for the dwc2 driver without my patch, when 
CONFIG_USB_DWC2_PERIPHERAL or CONFIG_USB_DWC2_DUAL_ROLE selected, if 
there were no phys or pdata defined, the driver probe will also return 
-EPROBE_DEFER. And when only CONFIG_USB_DWC2_HOST selected, the previous 
version driver didn't care any thing about phy, in my patch it will try 
to find a phy when platform driver probe, but do not fail probe if there 
isn't a phy node.


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