Hello,
On Wed, 16 Jan 2019 14:30:28 +0100, Paul Kocialkowski wrote:
> > Why is this conditional on the generic PHY lookup failing?
> >
> > Don't we simply want:
> >
> > ci->phy = devm_phy_get(dev->parent, "usb-phy");
> > ci->usb_phy = devm_usb_get_phy_by_phandle(dev->parent, "phys", 0);
> > if (IS_ERR(ci->usb_phy))
> > ci->usb_phy = devm_usb_get_phy(dev->parent, USB_PHY_TYPE_USB2);
> >
> > ?
>
> Well, the code dealing with the PHY later on will use ci->phy over ci-
> >usb_phy (so generic PHY API first). As a result, if the
> devm_usb_get_phy_by_phandle lookup fails but we got a generic PHY, the
> latter will be used and there is no need for a fallback. That's why I
> put both conditions there. Maybe that's too much of an assumption?
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)) {
/* Fall back to legacy USB PHY */
ci->usb_phy = devm_usb_get_phy_by_phandle(dev->parent, "phys",
0);
if (IS_ERR(ci->usb_phy))
ci->usb_phy = devm_usb_get_phy(dev->parent,
USB_PHY_TYPE_USB2);
}
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().
> > Does this needs a "Fixes:" tag ? It's not fixing a regression because
> > nobody complained until now, but it's really fixing a behavior that
> > wasn't correct.
>
> Yes I it this makes sense to consider that this was incorrect behavior
> starting from the moment the dt bindings were formalized for the
> driver, which would be commit d7d30c911dd957e274c3da6910d4286862ab1d78.
>
> Do you think that would nake sense?
Up to the maintainer I'd say. I don't have any preference here.
Thomas
--
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
