linux-kernel - Re: [PATCH 2/2] usb: core: phy: fix return value checking about devm_of_phy_get_by

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Date:   Mon, 25 Jun 2018 07:29:30 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     chunfeng.yun@...iatek.com, johan@...nel.org,
        gregkh@...uxfoundation.org, felipe.balbi@...ux.intel.com,
        matthias.bgg@...il.com, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 2/2] usb: core: phy: fix return value checking about
 devm_of_phy_get_by_index()

On Sun, Jun 24, 2018 at 08:00:01PM +0200, Martin Blumenstingl wrote:
> Hello Chunfeng,
> 
> thank you for the patch!
> 
> On Fri, Jun 22, 2018 at 8:33 AM Chunfeng Yun <chunfeng.yun@...iatek.com> wrote:

> > 2. devm_of_phy_get_by_index() should not fail for a valid index
> I have learned that the PHY framework can return -ENODEV if the PHY is:
> 1. supposed to be handled by the legacy USB PHY framework
> 2. the PHY node is disabled in devicetree
> 
> see [0] for the code in the PHY framework and [1] for the discussion
> with Johan (who informed me of case #1, I added him on this mail)
> 
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> > ---
> >  drivers/usb/core/phy.c | 11 ++++-------
> >  1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/usb/core/phy.c b/drivers/usb/core/phy.c
> > index 9879767..0f972e1 100644
> > --- a/drivers/usb/core/phy.c
> > +++ b/drivers/usb/core/phy.c
> > @@ -23,14 +23,11 @@ static int usb_phy_roothub_add_phy(struct device *dev, int index,
> >                                    struct list_head *list)
> >  {
> >         struct usb_phy_roothub *roothub_entry;
> > -       struct phy *phy = devm_of_phy_get_by_index(dev, dev->of_node, index);
> > +       struct phy *phy;
> >
> > -       if (IS_ERR_OR_NULL(phy)) {
> > -               if (!phy || PTR_ERR(phy) == -ENODEV)
> > -                       return 0;
> > -               else
> > -                       return PTR_ERR(phy);
> > -       }
> > +       phy = devm_of_phy_get_by_index(dev, dev->of_node, index);
> > +       if (IS_ERR(phy))
> > +               return PTR_ERR(phy);
> @Johan can you please review this as well? maybe we need to keep the
> -ENODEV check

Indeed, the -ENODEV check is still needed for the reasons you point out
above.

Johan