Re: [PATCH 5/5] powerpc: dts: remove label = "cpu" from DSA dt-binding

[Arınç ÜNAL]

On 4.12.2022 21:59, Vladimir Oltean wrote:
> Hi Pali,
>
> On Fri, Dec 02, 2022 at 08:35:52PM +0100, Pali Rohár wrote:
> > On Thursday 01 December 2022 17:44:00 Rob Herring wrote:
> > > On Thu, Dec 01, 2022 at 06:39:02PM +0100, Pali Rohár wrote:
> > > > I was told by Marek (CCed) that DSA port connected to CPU should have
> > > > label "cpu" and not "cpu<number>". Modern way for specifying CPU port is
> > > > by defining reference to network device, which there is already (&enet1
> > > > and &enet0). So that change just "fixed" incorrect naming cpu0 and cpu1.
> > > >
> > > > So probably linux kernel does not need label = "cpu" in DTS anymore. But
> > > > this is not the reason to remove this property. Linux kernel does not
> > > > use lot of other nodes and properties too... Device tree should describe
> > > > hardware and not its usage in Linux. "label" property is valid in device
> > > > tree and it exactly describes what or where is this node connected. And
> > > > it may be used for other systems.
> > > >
> > > > So I do not see a point in removing "label" properties from turris1x.dts
> > > > file, nor from any other dts file.
> > >
> > > Well, it seems like a bit of an abuse of 'label' to me. 'label' should
> > > be aligned with a sticker or other identifier identifying something to a
> > > human. Software should never care what the value of 'label' is.
> >
> > But it already does. "label" property is used for setting (initial)
> > network interface name for DSA drivers. And you can try to call e.g.
> > git grep '"cpu"' net/dsa drivers/net/dsa to see that cpu is still
> > present on some dsa places (probably relict or backward compatibility
> > before eth reference).
>
> Can you try to eliminate the word "probably" from the information you
> transmit and be specific about when did the DSA binding parse or require
> the 'label = "cpu"' property for CPU ports in any way?

As Jonas (on CC) pointed out, I only see this being used in the swconfig 
b53 driver which uses the label to identify the cpu port.

https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/generic/files/drivers/net/phy/b53/b53_common.c;h=87d731ec3e2a868dc8389f554b1dc9ab42c30be2;hb=HEAD#l1508

Maybe this got into DSA dt-bindings unchecked before it was decided to 
move forward with DSA instead of swconfig on Linux.

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