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SubjectRe: [PATCH] usb: chipidea: Grab the (legacy) USB PHY by phandle first
From
Date
Hi,

On Thu, 2019-01-17 at 06:44 +0000, Peter Chen wrote:
>
> > 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;
> }

Well I think this was more of a general outline than proper code to be
included in the driver anyway :)

I'm rather considering implementing what Thomas suggested at first,
which is going for the fallback even if a generic PHY was found, as to
stick more closely to the existing behavior.

Cheers,

Paul

> 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!
> >
>
>
--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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