linux-kernel - Re: [PATCH net-next v2 2/2] net: ethernet: mediatek: support custom GMAC label

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Message-ID: <CALCv0x2SG=0kBRnxfSPxi+FvaBK=QGPHQkHWHvTXOw64KawPUQ@mail.gmail.com>
Date:   Tue, 20 Apr 2021 12:57:43 -0700
From:   Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
To:     Rob Herring <robh@...nel.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Felix Fietkau <nbd@....name>,
        John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Mark Lee <Mark-MC.Lee@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        René van Dorst <opensource@...rst.com>
Subject: Re: [PATCH net-next v2 2/2] net: ethernet: mediatek: support custom
 GMAC label

On Tue, Apr 20, 2021 at 12:51 PM Rob Herring <robh@...nel.org> wrote:
>
> On Mon, Apr 19, 2021 at 08:46:59AM -0700, Ilya Lipnitskiy wrote:
> > The MAC device name can now be set within DTS file instead of always
> > being "ethX". This is helpful for DSA to clearly label the DSA master
> > device and distinguish it from DSA slave ports.
> >
> > For example, some devices, such as the Ubiquiti EdgeRouter X, may have
> > ports labeled ethX. Labeling the master GMAC with a different prefix
> > than DSA ports helps with clarity.
> >
> > Suggested-by: René van Dorst <opensource@...rst.com>
> > Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
> > ---
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > index 6b00c12c6c43..df3cda63a8c5 100644
> > --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > @@ -2845,6 +2845,7 @@ static const struct net_device_ops mtk_netdev_ops = {
> >
> >  static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
> >  {
> > +     const char *label = of_get_property(np, "label", NULL);
> >       const __be32 *_id = of_get_property(np, "reg", NULL);
> >       phy_interface_t phy_mode;
> >       struct phylink *phylink;
> > @@ -2867,9 +2868,10 @@ static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
> >               return -EINVAL;
> >       }
> >
> > -     eth->netdev[id] = alloc_etherdev(sizeof(*mac));
> > +     eth->netdev[id] = alloc_netdev(sizeof(*mac), label ? label : "eth%d",
> > +                                    NET_NAME_UNKNOWN, ether_setup);
>
> 'label' is generally supposed to correspond to the sticker for the
> device connector for a human to id. I can't really tell if that's the
> case here. I don't see how 'gmacX' vs. 'ethX' maps to DSA master vs.
> slave.
The ports on devices such as Ubiquiti ER-X are named eth0 through
eth4, all of them DSA slaves. The gmac (DSA master) is hard-coded to
eth0 without this change.
>
> I don't think this should be handled within a specific driver either. If
> we're going to have a way to name things, then fix it in
> alloc_etherdev().
>
> It can also be argued that device naming for userspace is a userspace
> (udev) problem.
Yeah, that is a valid argument. We can drop this changeset if the
agreement is that it doesn't belong in the specific driver or the
kernel-space at all.
Some discussion (and device picture) here if you are interested:
https://github.com/openwrt/openwrt/pull/3971

Ilya