netdev - Re: [PATCH net-next 4/8] net: phylink: update supported

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Message-ID: <YZaPyZ6VjTWvP1Kr@shell.armlinux.org.uk>
Date:   Thu, 18 Nov 2021 17:39:21 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Marek Behún <kabel@...nel.org>
Cc:     Andrew Lunn <andrew@...n.ch>, netdev@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH net-next 4/8] net: phylink: update supported_interfaces
 with modes from fwnode

On Thu, Nov 18, 2021 at 06:33:01PM +0100, Marek Behún wrote:
> On Thu, 18 Nov 2021 17:08:10 +0000
> "Russell King (Oracle)" <linux@...linux.org.uk> wrote:
> 
> > I'm quite certain that as we try to develop phylink, such as adding
> > extra facilities like specifying the interface modes, we're going to
> > end up running into these kinds of problems that we can't solve, and
> > we are going to have to keep compatibility for the old ways of doing
> > stuff going for years to come - which is just going to get more and
> > more painful.
> 
> One way to move this forward would be to check compatible of the
> corresponding MAC in this new function. If it belongs to an unconverted
> driver, we can ensure the old behaviour. This would require to add a
> comment to the driver saying "if you convert this, please drop the
> exception in phylink_update_phy_modes()".

That could work when drivers pass the fwnode as the "device" node.
Some drivers don't do that, they pass a sub-node instead - such as
mvpp2. However, mvpp2 is of course up to date with all phylink
developments.

However, the same issue exists with DSA - the fwnode passed to
phylink doesn't have a compatible. I suppose we could walk up the
fwnode tree until we do find a node with a compatible property,
that may work.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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