linux-kernel - Re: [PATCH net-next] net: dsa: mv88e6xxx: Fix validation of built-in PHYs on 6095/6097

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Message-ID: <YgkwHqjMq5DtoMd1@shell.armlinux.org.uk>
Date:   Sun, 13 Feb 2022 16:21:50 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Tobias Waldekranz <tobias@...dekranz.com>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Marek Behún <kabel@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: dsa: mv88e6xxx: Fix validation of built-in
 PHYs on 6095/6097

On Sun, Feb 13, 2022 at 04:32:51PM +0100, Tobias Waldekranz wrote:
> On Sun, Feb 13, 2022 at 12:58, "Russell King (Oracle)" <linux@...linux.org.uk> wrote:
> > I'm wondering what the point of checking the cmode here is - if the port
> > is internal, won't this switch always have cmode == PHY?
> 
> For all intents and purposes: I think so. It is just that the functional
> spec. also lists cmode == 4 == disabled (PHYDetect == 0) for the
> internal ports. So I figured that there might be some way of strapping
> ports as disabled that I had never come across.

I don't think there is a way to pinstrap the internal ports. As far as
I can see, the only way would be for software to program PHY Detect to
zero.

If we wanted a port to be disabled, then describing it in firmware as
being enabled would be a bug. If it isn't described in firmware, the
DSA code won't even consider looking at the port.

> Do you think we should drop it?

I think so.

Thanks.

-- 
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