linux-kernel - Re: [PATCH 1/3] net: ocelot: add support to get mac from device-tree

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Date:   Thu, 28 Oct 2021 14:51:43 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Clément Léger <clement.leger@...tlin.com>
CC:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        Andrew Lunn <andrew@...n.ch>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] net: ocelot: add support to get mac from device-tree

On Thu, Oct 28, 2021 at 04:38:25PM +0200, Clément Léger wrote:
> Le Thu, 28 Oct 2021 14:22:55 +0000,
> Vladimir Oltean <vladimir.oltean@....com> a écrit :
> 
> > On Thu, Oct 28, 2021 at 04:15:22PM +0200, Clément Léger wrote:
> > > Le Thu, 28 Oct 2021 14:06:12 +0000,
> > > Vladimir Oltean <vladimir.oltean@....com> a écrit :
> > >   
> > > > On Thu, Oct 28, 2021 at 03:49:30PM +0200, Clément Léger wrote:  
> > > > > Add support to get mac from device-tree using
> > > > > of_get_mac_address.
> > > > > 
> > > > > Signed-off-by: Clément Léger <clement.leger@...tlin.com>
> > > > > ---
> > > > >  drivers/net/ethernet/mscc/ocelot_vsc7514.c | 5 ++++-
> > > > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
> > > > > b/drivers/net/ethernet/mscc/ocelot_vsc7514.c index
> > > > > d51f799e4e86..c39118e5b3ee 100644 ---
> > > > > a/drivers/net/ethernet/mscc/ocelot_vsc7514.c +++
> > > > > b/drivers/net/ethernet/mscc/ocelot_vsc7514.c @@ -526,7 +526,10
> > > > > @@ static int ocelot_chip_init(struct ocelot *ocelot, const
> > > > > struct ocelot_ops *ops) ocelot_pll5_init(ocelot);
> > > > >  
> > > > > -	eth_random_addr(ocelot->base_mac);
> > > > > +	ret = of_get_mac_address(ocelot->dev->of_node,
> > > > > ocelot->base_mac);    
> > > > 
> > > > Why not per port? This is pretty strange, I think.  
> > > 
> > > Hi Vladimir,
> > > 
> > > Currently, all ports share the same base mac address (5 first
> > > bytes). The final mac address per port is computed in
> > > ocelot_probe_port by adding the port number as the last byte of the
> > > mac_address provided.
> > > 
> > > Clément  
> > 
> > Yes, I know that, but that's not my point.
> > Every switch port should be pretty much compliant with
> > ethernet-controller.yaml, if it could inherit that it would be even
> > better. And since mac-address is an ethernet-controller.yaml property,
> > it is pretty much non-obvious at all that you put the mac-address
> > property directly under the switch, and manually add 0, 1, 2, 3 etc
> > to it. My request was to parse the mac-address property of each port.
> > Like this:
> > 
> > base_mac = random;
> > 
> > for_each_port() {
> > 	err = of_get_mac_address(port_dn, &port_mac);
> > 	if (err)
> > 		port_mac = base_mac + port;
> > }
> 
> Ok indeed. So I will parse each port for a mac-address property. Do you
> also want a fallback to use the switch base mac if not specified in
> port or should I keep the use of a default random mac as the base
> address anyway ?

Isn't the pseudocode I posted above explicit enough? Sorry...
Keep doing what the driver is doing right now, with an optional
mac-address override per port.
Why would we read the mac-address property of the switch? Which other
switch driver does that? Are there device trees in circulation where
this is being done?

> > > > > +	if (ret)
> > > > > +		eth_random_addr(ocelot->base_mac);
> > > > > +
> > > > >  	ocelot->base_mac[5] &= 0xf0;
> > > > >  
> > > > >  	return 0;
> > > > > -- 
> > > > > 2.33.0  
> > > >     
> >   
>