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Date: Sat, 13 Sep 2014 00:59:34 +0000
From: Peter Chen <Peter.Chen@...escale.com>
To: Antoine Tenart <antoine.tenart@...e-electrons.com>
CC: "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 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;
> > >
>
Both of our implementation work, ok, use yours.
Peter
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