[PATCH] powerpc/kmcent2: update the ethernet devices' phy properties

[Madalin-cristian Bucur]

> -----Original Message-----
> From: Scott Wood <oss at buserror.net>
> Sent: Wednesday, August 28, 2019 7:19 AM
> To: Valentin Longchamp <valentin at longchamp.me>; Madalin-cristian Bucur
> <madalin.bucur at nxp.com>
> Cc: linuxppc-dev at lists.ozlabs.org; galak at kernel.crashing.org;
> netdev at vger.kernel.org
> Subject: Re: [PATCH] powerpc/kmcent2: update the ethernet devices' phy
> properties
> 
> On Thu, 2019-08-08 at 23:09 +0200, Valentin Longchamp wrote:
> > Le mar. 30 juil. 2019 à 11:44, Madalin-cristian Bucur
> > <madalin.bucur at nxp.com> a écrit :
> > >
> > > > -----Original Message-----
> > > >
> > > > > Le dim. 14 juil. 2019 à 22:05, Valentin Longchamp
> > > > > <valentin at longchamp.me> a écrit :
> > > > > >
> > > > > > Change all phy-connection-type properties to phy-mode that are
> > > > > > better
> > > > > > supported by the fman driver.
> > > > > >
> > > > > > Use the more readable fixed-link node for the 2 sgmii links.
> > > > > >
> > > > > > Change the RGMII link to rgmii-id as the clock delays are added
> by
> > > > > > the
> > > > > > phy.
> > > > > >
> > > > > > Signed-off-by: Valentin Longchamp <valentin at longchamp.me>
> > > >
> > > > I don't see any other uses of phy-mode in arch/powerpc/boot/dts/fsl,
> and
> > > > I see
> > > > lots of phy-connection-type with fman.  Madalin, does this patch
> look
> > > > OK?
> > > >
> > > > -Scott
> > >
> > > Hi,
> > >
> > > we are using "phy-connection-type" not "phy-mode" for the NXP (former
> > > Freescale)
> > > DPAA platforms. While the two seem to be interchangeable ("phy-mode"
> seems
> > > to be
> > > more recent, looking at the device tree bindings), the driver code in
> > > Linux seems
> > > to use one or the other, not both so one should stick with the variant
> the
> > > driver
> > > is using. To make things more complex, there may be dependencies in
> > > bootloaders,
> > > I see code in u-boot using only "phy-connection-type" or only "phy-
> mode".
> > >
> > > I'd leave "phy-connection-type" as is.
> >
> > So I have finally had time to have a look and now I understand what
> > happens. You are right, there are bootloader dependencies: u-boot
> > calls fdt_fixup_phy_connection() that somehow in our case adds (or
> > changes if already in the device tree) the phy-connection-type
> > property to a wrong value ! By having a phy-mode in the device tree,
> > that is not changed by u-boot and by chance picked up by the kernel
> > fman driver (of_get_phy_mode() ) over phy-connection-mode, the below
> > patch fixes it for us.
> >
> > I agree with you, it's not correct to have both phy-connection-type
> > and phy-mode. Ideally, u-boot on the board should be reworked so that
> > it does not perform the above wrong fixup. However, in an "unfixed"
> > .dtb (I have disabled fdt_fixup_phy_connection), the device tree in
> > the end only has either phy-connection-type or phy-mode, according to
> > what was chosen in the .dts file. And the fman driver works well with
> > both (thanks to the call to of_get_phy_mode() ). I would therefore
> > argue that even if all other DPAA platforms use phy-connection-type,
> > phy-mode is valid as well. (Furthermore we already have hundreds of
> > such boards in the field and we don't really support "remote" u-boot
> > update, so the u-boot fix is going to be difficult for us to pull).
> >
> > Valentin
> 
> Madalin, are you OK with the patch given this explanation?
> 
> -Scott
> 

Yes, I understand that it's the only option they have, given the inability
to upgrade u-boot (this may prove to be an issue in the future, in other
situations).

Acked-by: Madalin Bucur <madalin.bucur at nxp.com>