Messages in this thread | | | Date | Tue, 5 Sep 2023 14:00:21 +0300 | Subject | Re: [PATCH 2/4] dt-bindings: net: dsa: document internal MDIO bus | From | Arınç ÜNAL <> |
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On 5.09.2023 05:42, Luiz Angelo Daros de Luca wrote: >>> [1] ...this. The SMI-controlled and MDIO-controlled Realtek switches are >>> otherwise the same, right? So why would they have different dt-bindings? >> >> Honestly, I'm wondering the answer to this as well. For some reason, when >> probing the SMI controlled Realtek switches, instead of just letting >> dsa_switch_setup() populate ds->slave_mii_bus, on realtek_smi_setup_mdio() >> on realtek-smi.c: >> >> - priv->slave_mii_bus is allocated. >> - mdio_np = of_get_compatible_child(priv->dev->of_node, "realtek,smi-mdio"); >> - priv->slave_mii_bus->dev.of_node = mdio_np; >> - ds->slave_mii_bus = priv->slave_mii_bus; > > I might be able to help here. The Realtek SMI version created a custom > slave_mii driver because it was the only way to associate it with an > MDIO DT node. And that DT node was required to specify the interrupts > for each phy0. > It would work without that mdio node, letting DSA setup handle the > slave bus, but it would rely only on polling for port status. > > As we only have a single internal MDIO, the compatible string > "realtek,smi-mdio" would not be necessary if the driver checks for a > "mdio"-named child node. Maybe the code was just inspired by another > DSA driver that uses more MDIO buses or external ones. The "mdio" name > is suggested by docs since it was committed > (https://www.kernel.org/doc/Documentation/devicetree/bindings/net/dsa/realtek-smi.txt). > That name was also kept in the YAML translation > (https://www.kernel.org/doc/Documentation/devicetree/bindings/net/dsa/realtek.yaml). > > The Realtek MDIO driver was merged at the same release that included > the change that allows dsa_switch_setup() to reference the "mdio" > OF-node if present. That way, it could avoid creating a custom > slave_mii_bus driver. > > I submitted a small series of patches to unify that behavior between > those two drivers: > > https://lore.kernel.org/netdev/CAJq09z44SNGFkCi_BCpQ+3DuXhKfGVsMubRYE7AezJsGGOboVA@mail.gmail.com/ > (This is my answer to the series opening message to include the first > paragraph ate by the editor) > > There was some discussion but not NAC, ACK or RFC. It would have > dropped some lines of code. I can revive it if there is interest.
I'd like this to happen, thanks Luiz!
Arınç
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