Re: net: dsa: Realtek switch drivers

[Linus Walleij]

On Fri, Jun 14, 2024 at 3:49 AM Chris Packham
<Chris.Packham@xxxxxxxxxxxxxxxxxxx> wrote:

> I'm starting to look at some L2/L3 switches with Realtek silicon. I see
> in the upstream kernel there are dsa drivers for a couple of simple L2
> switches. While openwrt has support for a lot of the more advanced
> silicon. I'm just wondering if there is a particular reason no-one has
> attempted to upstream support for these switches?

It began with the RTL8366RB ("RTL8366 revision B") which I think is
equivalent to RTL8366S as well, but have not been able to test.

Then Luiz and Alvin jumped in and fixed up the RTL8365MB family.

So the support is pretty much what is stated in the DT bindings
in Documentation/devicetree/bindings/net/dsa/realtek.yaml:

properties:
  compatible:
    enum:
      - realtek,rtl8365mb
      - realtek,rtl8366rb
    description: |
      realtek,rtl8365mb:
        Use with models RTL8363NB, RTL8363NB-VB, RTL8363SC, RTL8363SC-VB,
        RTL8364NB, RTL8364NB-VB, RTL8365MB, RTL8366SC, RTL8367RB-VB, RTL8367S,
        RTL8367SB, RTL8370MB, RTL8310SR
      realtek,rtl8366rb:
        Use with models RTL8366RB, RTL8366S

It may look like just RTL8365 and RTL8366 on the surface but the sub-version
is detected at runtime.

> If I were to start
> grabbing drivers from openwrt and trying to get them landed would that
> be a problem?

I think the base is there, when I started with RTL8366RB it was pretty
uphill but the kernel DSA experts (Vladimir & Andrew especially) are super
helpful so eventually we have arrived at something that works reasonably.

The RTL8356MB-family driver is more advanced and has a lot more features,
notably it supports all known RTL8367 variants.

The upstream OpenWrt in target/linux/generic/files/drivers/net/phy
has the following drivers for the old switchdev:
-rw-r--r--. 1 linus linus 25382 Jun  7 21:44 rtl8306.c
-rw-r--r--. 1 linus linus 40268 Jun  7 21:44 rtl8366rb.c
-rw-r--r--. 1 linus linus 33681 Jun  7 21:44 rtl8366s.c
-rw-r--r--. 1 linus linus 36324 Jun  7 21:44 rtl8366_smi.c
-rw-r--r--. 1 linus linus  4838 Jun  7 21:44 rtl8366_smi.h
-rw-r--r--. 1 linus linus 58021 Jun 12 18:50 rtl8367b.c
-rw-r--r--. 1 linus linus 59612 Jun 12 18:50 rtl8367.c

As far as I can tell we cover all but RTL8306 with the current in-tree
drivers, the only reason these are still in OpenWrt would be that some
boards are not migrated to DSA.

But maybe I missed something?

Yours,
Linus Walleij