Re: R: [PATCH v2 4/4] dt-bindings: net: Document use of mac-address-increment
From: Andrew Lunn
Date: Sat Sep 19 2020 - 21:48:18 EST
On Sun, Sep 20, 2020 at 02:39:39AM +0200, ansuelsmth@xxxxxxxxx wrote:
> > -----Messaggio originale-----
> > Da: Andrew Lunn <andrew@xxxxxxx>
> > Inviato: domenica 20 settembre 2020 02:31
> > A: Ansuel Smith <ansuelsmth@xxxxxxxxx>
> > Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>; Richard Weinberger
> > <richard@xxxxxx>; Vignesh Raghavendra <vigneshr@xxxxxx>; Rob Herring
> > <robh+dt@xxxxxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Jakub
> > Kicinski <kuba@xxxxxxxxxx>; Heiner Kallweit <hkallweit1@xxxxxxxxx>;
> > Russell King <linux@xxxxxxxxxxxxxxx>; Frank Rowand
> > <frowand.list@xxxxxxxxx>; Boris Brezillon <bbrezillon@xxxxxxxxxx>; linux-
> > mtd@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx
> > Oggetto: Re: [PATCH v2 4/4] dt-bindings: net: Document use of mac-
> > address-increment
> > > + mac-address-increment:
> > > + description:
> > > + The MAC address can optionally be increased (or decreased using
> > > + negative values) from the original value readed (from a nvmem
> > Read is irregular, there is no readed, just read.
> > > + for example). This can be used if the mac is readed from a
> > > + partition and must be increased based on the number of device
> > > + present in the system.
> > You should probably add there is no underflow/overflow to other bytes
> > of the MAC address. 00:01:02:03:04:ff + 1 == 00:01:02:03:04:00.
> > > + minimum: -255
> > > + maximum: 255
> > > +
> > > + mac-address-increment-byte:
> > > + description:
> > > + If 'mac-address-increment' is defined, this will tell what byte
> > > + the mac-address will be increased. If 'mac-address-increment' is
> > > + not defined, this option will do nothing.
> > > + default: 5
> > > + minimum: 0
> > > + maximum: 5
> > Is there a real need for this? A value of 0 seems like a bad idea,
> > since a unicast address could easily become a multicast address, which
> > is not valid for an interface address. It also does not seem like a
> > good idea to allow the OUI to be changed. So i think only bytes 3-5
> > should be allowed, but even then, i don't think this is needed, unless
> > you do have a clear use case.
> > Andrew
> Honestly the mac-address-increment-byte is added to give user some control
> but I
> don't really have a use case for it. Should I limit it to 3 or just remove
> the function?
If you have no use case, just remove it and document that last byte
will be incremented. I somebody does need it, it can be added in a
backwards compatible way.