Thread (30 messages) 30 messages, 15 authors, 2022-12-07

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

From: Arınç ÜNAL <hidden>
Date: 2022-12-05 19:17:42
Also in: linux-devicetree, lkml, netdev

On 4.12.2022 21:59, Vladimir Oltean wrote:
Hi Pali,

On Fri, Dec 02, 2022 at 08:35:52PM +0100, Pali Rohár wrote:
quoted
On Thursday 01 December 2022 17:44:00 Rob Herring wrote:
quoted
On Thu, Dec 01, 2022 at 06:39:02PM +0100, Pali Rohár wrote:
quoted
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.

Arınç
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