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SubjectRe: [RFC] net: dsa: qca8k: implement rgmii-id mode
On Fri, Feb 15, 2019 at 04:01:08PM +0100, Michal Vokáč wrote:
> Hi,
>
> networking on my boards [1], which are currently in linux-next, suddently
> stopped working. I tracked it down to this commit 5ecdd77c61c8 ("net: dsa:
> qca8k: disable delay for RGMII mode") [2].
>
> So I think the rgmii-id mode is obviously needed in my case.
> I was able to find a couple drivers that read tx/rx-delay or
> tx/rx-internal-delay from device tree. Namely:
>
> drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
> drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
> drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
> drivers/net/phy/dp83867.c
>
> I would appreciate any hints how to add similar function to qca8k driver
> if that is the correct way to go. Can I take some of the above mentioned
> drivers as a good example for that? How should the binding look like?
>
> I would expect something like this:
>
> switch@0 {
> compatible = "qca,qca8334";
> reg = <0>;
>
> switch_ports: ports {
> #address-cells = <1>;
> #size-cells = <0>;
>
> ethphy0: port@0 {
> reg = <0>;
> label = "cpu";
> phy-mode = "rgmii-id";
> qca,tx-delay = <3>;
> qca,rx-delay = <3>;
> ethernet = <&fec>;
> };

Hi Michal

Your submission used:

+ ethphy0: port@0 {
+ reg = <0>;
+ label = "cpu";
+ phy-mode = "rgmii";
+ ethernet = <&fec>;
+
+ fixed-link {
+ speed = <1000>;
+ full-duplex;
+ };
+ };

This is good. If you have a fixed-link you can pass a phy-mode.

The comment that was removed was:

- /* According to the datasheet, RGMII delay is enabled through
- * PORT5_PAD_CTRL for all ports, rather than individual port
- * registers
- */

Is it possible to enable delays per port? Ideally, you want to enable
delays for just selected ports. Add another case for
PHY_INTERFACE_MODE_RGMII_ID to enable the delays.

Andrew

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