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

From: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
To: Rob Herring <robh@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Felix Fietkau" <nbd@nbd.name>, "John Crispin" <john@phrozen.org>,
	"Sean Wang" <sean.wang@mediatek.com>,
	"Mark Lee" <Mark-MC.Lee@mediatek.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Russell King" <linux@armlinux.org.uk>,
	netdev@vger.kernel.org,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	"René van Dorst" <opensource@vdorst.com>
Subject: Re: [PATCH net-next v2 2/2] net: ethernet: mediatek: support custom GMAC label
Date: Tue, 20 Apr 2021 12:57:43 -0700	[thread overview]
Message-ID: <CALCv0x2SG=0kBRnxfSPxi+FvaBK=QGPHQkHWHvTXOw64KawPUQ@mail.gmail.com> (raw)
In-Reply-To: <20210420195132.GA3686955@robh.at.kernel.org>

On Tue, Apr 20, 2021 at 12:51 PM Rob Herring <robh@kernel.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@vdorst.com>
> > Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.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