Re: realtek PHY commit bbc4d71d63549 causes regression

From: Ard Biesheuvel <ardb@kernel.org>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "open list:BPF JIT for MIPS (32-BIT AND 64-BIT)" 
	<netdev@vger.kernel.org>,
	Ilias Apalodimas <ilias.apalodimas@linaro.org>,
	Willy Liu <willy.liu@realtek.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Sasha Levin <sashal@kernel.org>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Masahisa Kojima <masahisa.kojima@linaro.org>
Subject: Re: realtek PHY commit bbc4d71d63549 causes regression
Date: Sat, 17 Oct 2020 17:18:16 +0200	[thread overview]
Message-ID: <CAMj1kXH+Z56dkZz8OYMhPuqbjPPCqW=UMV6w--=XXh87UyHVaQ@mail.gmail.com> (raw)
In-Reply-To: <20201017151132.GK456889@lunn.ch>

On Sat, 17 Oct 2020 at 17:11, Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Sat, Oct 17, 2020 at 04:46:23PM +0200, Ard Biesheuvel wrote:
> > On Sat, 17 Oct 2020 at 16:44, Andrew Lunn <andrew@lunn.ch> wrote:
> > >
> > > On Sat, Oct 17, 2020 at 04:20:36PM +0200, Ard Biesheuvel wrote:
> > > > Hello all,
> > > >
> > > > I just upgraded my arm64 SynQuacer box to 5.8.16 and lost all network
> > > > connectivity.
> > >
> > > Hi Ard
> > >
> > > Please could you point me at the DT files.
> > >
> > > > This box has a on-SoC socionext 'netsec' network controller wired to
> > > > a Realtek 80211e PHY, and this was working without problems until
> > > > the following commit was merged
> > >
> > > It could be this fix has uncovered a bug in the DT file. Before this
> > > fix, if there is an phy-mode property in DT, it could of been ignored.
> > > Now the phy-handle property is correctly implemented. So it could be
> > > the DT has the wrong value, e.g. it has rgmii-rxid when maybe it
> > > should have rgmii-id.
> > >
> >
> > This is an ACPI system. The phy-mode device property is set to 'rgmii'
>
> Hi Ard
>
> Please try rgmii-id.
>
> Also, do you have the schematic? Can you see if there are any
> strapping resistors? It could be, there are strapping resistors to put
> it into rgmii-id. Now that the phy-mode properties is respected, the
> reset defaults are being over-written to rgmii, which breaks the link.
> Or the bootloader has already set the PHY mode to rgmii-id.
>
> You can also use '' as the phy-mode, which results in
> PHY_INTERFACE_MODE_NA, which effectively means, don't touch the PHY
> mode, something else has already set it up. This might actually be the
> correct way to go for ACPI. In the DT world, we tend to assume the
> bootloader has done the absolute minimum and Linux should configure
> everything. The ACPI takes the opposite view, the firmware will do the
> basic hardware configuration, and Linux should not touch it, or ask
> ACPI to modify it.
>

Indeed, the firmware should have set this up. This would mean we could
do this in the driver: it currently uses

priv->phy_interface = device_get_phy_mode(&pdev->dev);

Can we just assign that to PHY_INTERFACE_MODE_NA instead?