linux-kernel - Re: [PATCH v4 9/9] usb: chipidea: add support to the generic PHY framework in ChipIdea

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Message-ID: <20140912093550.GC18774@kwain>
Date:	Fri, 12 Sep 2014 11:35:50 +0200
From:	Antoine Tenart <antoine.tenart@...e-electrons.com>
To:	Peter Chen <peter.chen@...escale.com>
Cc:	Antoine Tenart <antoine.tenart@...e-electrons.com>,
	"balbi@...com" <balbi@...com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"kishon@...com" <kishon@...com>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"sergei.shtylyov@...entembedded.com" 
	<sergei.shtylyov@...entembedded.com>,
	"yoshihiro.shimoda.uh@...esas.com" <yoshihiro.shimoda.uh@...esas.com>,
	"alexandre.belloni@...e-electrons.com" 
	<alexandre.belloni@...e-electrons.com>,
	"thomas.petazzoni@...e-electrons.com" 
	<thomas.petazzoni@...e-electrons.com>,
	"zmxu@...vell.com" <zmxu@...vell.com>,
	"jszhang@...vell.com" <jszhang@...vell.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 9/9] usb: chipidea: add support to the generic PHY
 framework in ChipIdea

On Fri, Sep 12, 2014 at 05:27:13PM +0800, Peter Chen wrote:
> On Fri, Sep 12, 2014 at 10:21:25AM +0200, Antoine Tenart wrote:
> > Peter,
> > 
> > On Fri, Sep 12, 2014 at 01:10:33AM +0000, Peter Chen wrote:
> > > > On Thu, Sep 11, 2014 at 08:54:47AM +0800, Peter Chen wrote:
> > > > > On Wed, Sep 03, 2014 at 09:40:40AM +0200, Antoine Tenart wrote:
> > > > > > @@ -595,23 +639,27 @@ static int ci_hdrc_probe(struct platform_device
> > > > *pdev)
> > > > > >  		return -ENODEV;
> > > > > >  	}
> > > > > >
> > > > > > -	if (ci->platdata->usb_phy)
> > > > > > +	if (ci->platdata->phy)
> > > > > > +		ci->phy = ci->platdata->phy;
> > > > > > +	else if (ci->platdata->usb_phy)
> > > > > >  		ci->usb_phy = ci->platdata->usb_phy;
> > > > > >  	else
> > > > > > -		ci->usb_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> > > > > > +		ci->phy = devm_phy_get(dev, "usb-phy");
> > > > > >
> > > > > > -	if (IS_ERR(ci->usb_phy)) {
> > > > > > -		ret = PTR_ERR(ci->usb_phy);
> > > > > > +	if (IS_ERR(ci->phy) || (ci->phy == NULL && ci->usb_phy == NULL)) {
> > > > > >  		/*
> > > > > >  		 * if -ENXIO is returned, it means PHY layer wasn't
> > > > > >  		 * enabled, so it makes no sense to return -EPROBE_DEFER
> > > > > >  		 * in that case, since no PHY driver will ever probe.
> > > > > >  		 */
> > > > > > -		if (ret == -ENXIO)
> > > > > > -			return ret;
> > > > > > +		if (PTR_ERR(ci->phy) == -ENXIO)
> > > > > > +			return -ENXIO;
> > > > > >
> > > > > > -		dev_err(dev, "no usb2 phy configured\n");
> > > > > > -		return -EPROBE_DEFER;
> > > > > > +		ci->usb_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> > > > > > +		if (IS_ERR(ci->usb_phy)) {
> > > > > > +			dev_err(dev, "no usb2 phy configured\n");
> > > > > > +			return -EPROBE_DEFER;
> > > > > > +		}
> > > > > >  	}
> > > > >
> > > > > Sorry, I can't accept this change, why devm_usb_get_phy(dev,
> > > > > USB_PHY_TYPE_USB2) is put at error path? Since current get PHY
> > > > > operation is a little complicated, we may have a dedicate function to do it,
> > > > dwc3 driver is a good example.
> > > > 
> > > > It's not the error path, it's the case when there is no PHY from the generic PHY
> > > > framework available. Getting an USB PHY is a fallback solution.
> > > > 
> > > > I agree we can move this to a dedicated function. But even if doing so, we'll
> > > > have to test ci->phy first.
> > > > 
> > > > Or do you have something else in mind?
> > > > 
> > >  
> > > I still want devm_usb_get_phy(dev, USB_PHY_TYPE_USB2) to be called at the same place
> > > like generic_phy, not in later error path, in error path, we only handle error.
> > 
> > Would this fit you?
> > 
> > if (ci->platdata->phy)
> >         ci->phy = ci->platdata->phy;
> > else if (ci->platdata->usb_phy)
> >         ci->usb_phy = ci->platdata->usb_phy;
> > 
> > if (ci->phy == NULL && ci->usb_phy == NULL) {
> 
> You should use else if here.

Yes, sure.

> 
> >         ci->phy = devm_phy_get(dev, "usb-phy");
> >         ci->usb_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> > 
> >         /* if both generic PHY and USB PHY layers aren't enabled */
> >         if (PTR_ERR(ci->phy) == -ENOSYS && PTR_ERR(ci->usb_phy) == -ENXIO)
> >                 return -ENXIO;
> > 
> >         if (IS_ERR(ci->phy) && IS_ERR(ci->usb_phy))
> >                 return -EPROBE_DEFER;
> > 
> >         /* if an usb_phy is available, but no phy is there */
> >         if (PTR_ERR(ci->phy) == -ENODEV)
> >                 ci->phy = NULL;
> 	if (ci->phy)
> 		ci->usb_phy = NULL;
> 	if (ci->usb_phy)
> 		ci->phy = NULL;
> 
> How about above?

When no PHY or USB PHY is found, -ENODEV is returned. Doing the above
would always end up having ci->phy and ci->usb_phy being NULL.

We could have:

	if (IS_ERR(ci->phy))
		ci->phy = NULL;
	else if (IS_ERR(ci->usb_phy))
		ci->usb_phy = NULL;


Antoine

-- 
Antoine Ténart, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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