linux-kernel - Re: [PATCH v3] lan743x: correctly handle chips with internal PHY

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Date:   Sun, 8 Nov 2020 16:57:56 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Sven Van Asbroeck <thesven73@...il.com>
Cc:     Bryan Whitehead <bryan.whitehead@...rochip.com>,
        David S Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        Roelof Berg <rberg@...g-solutions.de>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] lan743x: correctly handle chips with internal PHY

On Sun, Nov 08, 2020 at 09:06:53AM -0500, Sven Van Asbroeck wrote:
> From: Sven Van Asbroeck <thesven73@...il.com>
> 
> Commit 6f197fb63850 ("lan743x: Added fixed link and RGMII support")
> assumes that chips with an internal PHY will never have a devicetree
> entry. This is incorrect: even for these chips, a devicetree entry
> can be useful e.g. to pass the mac address from bootloader to chip:
> 
>     &pcie {
>             status = "okay";
> 
>             host@0 {
>                     reg = <0 0 0 0 0>;
> 
>                     #address-cells = <3>;
>                     #size-cells = <2>;
> 
>                     lan7430: ethernet@0 {
>                             /* LAN7430 with internal PHY */
>                             compatible = "microchip,lan743x";
>                             status = "okay";
>                             reg = <0 0 0 0 0>;
>                             /* filled in by bootloader */
>                             local-mac-address = [00 00 00 00 00 00];
>                     };
>             };
>     };
> 
> If a devicetree entry is present, the driver will not attach the chip
> to its internal phy, and the chip will be non-operational.
> 
> Fix by tweaking the phy connection algorithm:
> - first try to connect to a phy specified in the devicetree
>   (could be 'real' phy, or just a 'fixed-link')
> - if that doesn't succeed, try to connect to an internal phy, even
>   if the chip has a devnode
> 
> Tested on a LAN7430 with internal PHY. I cannot test a device using
> fixed-link, as I do not have access to one.
> 
> Fixes: 6f197fb63850 ("lan743x: Added fixed link and RGMII support")
> Tested-by: Sven Van Asbroeck <thesven73@...il.com> # lan7430
> Signed-off-by: Sven Van Asbroeck <thesven73@...il.com>
> ---
> 
> v2 -> v3:
>     Andrew Lunn: make patch truly minimal.

This is looking much better. Thanks.

> 
> v1 -> v2:
>     Andrew Lunn: keep patch minimal and correct, so keep open-coded version
>     of of_phy_get_and_connect().
> 
>     Jakub Kicinski: fix e-mail address case.
> 
> Tree: v5.10-rc2

Since this is a networking fix, it should be against:

git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git

Please also put in the subject [PATCH net v4] to make it clear it is
for the net tree. You can find more about this here:

https://www.kernel.org/doc/html/latest/networking/netdev-FAQ.html

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew