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

[Antoine Tenart]

On Fri, Sep 12, 2014 at 06:28:29PM +0800, Peter Chen wrote:
> On Fri, Sep 12, 2014 at 11:35:50AM +0200, Antoine Tenart wrote:
> > 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.
> 
> When we try to get generic phy, if -ENODEV is returned, the ci->usb_phy
> should not be NULL, otherwise, your the second condition will return 
> -EPROBE_DEFER, it means when the code goes here, there must be one PHY
> is found.

We first call devm_phy_get() and devm_usb_get_phy(), ci->phy and
ci->usb_phy can't be NULL after this.

Then the "if (IS_ERR(ci->phy) && IS_ERR(ci->usb_phy))" ensure at least
one of them is a valid PHY.

I don't see the problem here. Am I missing something?

> 
> > 
> > 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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