linux-kernel - RE: [PATCH] usb: chipidea: Grab the (legacy) USB PHY by phandle first

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Date:   Thu, 17 Jan 2019 06:44:24 +0000
From:   Peter Chen <peter.chen@....com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: RE: [PATCH] usb: chipidea: Grab the (legacy) USB PHY by phandle first

 
> 
> On Wed, 2019-01-16 at 14:44 +0100, Thomas Petazzoni wrote:
> > Well prior to your code, there was already a possibility for both
> > ci->phy and ci->usb_phy to be valid. I don't think it's really useful
> > to avoid the fallback when a generic PHY has already been found, it's
> > confusing. If really you want to clarify that, it should be:
> >
> > 	/* Let's first try to find a generic PHY */
> > 	ci->phy = devm_phy_get(dev->parent, "usb-phy");
> > 	if (IS_ERR(ci->phy)) {

Please consider -EPROBE_DEFER case

> > 		/* Fall back to legacy USB PHY */
> > 		ci->usb_phy = devm_usb_get_phy_by_phandle(dev->parent, "phys",
> 0);

Please consider -EPROBE_DEFER case

> > 		if (IS_ERR(ci->usb_phy))
> > 			ci->usb_phy = devm_usb_get_phy(dev->parent,
> USB_PHY_TYPE_USB2);
> > 	}
> >

Below code 
                if (IS_ERR(ci->phy) && IS_ERR(ci->usb_phy)) {
                        ret = -EPROBE_DEFER;
                        goto ulpi_exit;
                }    

needs to change as:

                if (PTR_ERR(ci->phy) ==-EPROBE_DEFER  ||  PTR_ERR(ci->usb_phy) == -EPROBE_DEFER) {
                        ret = -EPROBE_DEFER;
                        goto ulpi_exit;
                }    

Peter

> > With that, you would only have either ci->phy or ci->usb_phy be valid,
> > and never both. With  your change, you can have ci->phy and
> > ci->usb_phy both be valid if the legacy USB PHY was found using
> > devm_usb_get_phy_by_phandle(), but not if we fell back to
> > devm_usb_get_phy().
> 
> Okay that makes sense, your suggestion is indeed more consistent with the existing
> behavior. I'll go with that in the next revision!
>