Re: [linux-next-v2 1/5] arm64: dts: rockchip: Fix gmac phy mode to rgmii on Rock 3A SBC.

Peter Geis
2022-11-16T20:38:53Z

On Wed, Nov 16, 2022 at 3:02 PM Anand Moon <linux.amoon@gmail.com> wrote:
>
> On rk356x ethernet phy support reduced media independent interface (RMII)
> and reduced gigabit media independent interface (RGMII).
> So set the phy mode to rgmii to support clock delay, also
> add TX and RX delay for phy-mode.

Controller based clock delay, the various rgmii-id modes (rgmii-txid
and rgmii-rxid are also valid) apply the delays in the phy. They are
usually at a fixed amount, but some phys support variable delays.

You want your commit message to accurately describe the problem, such
as "In rgmii-id mode, the phy on the rock-3a is unreliable due to
incorrect delays. Switch to rgmii mode in order to handle the delays
in the controller."

>
> Fix following warning
>
> [ 7.365215] rk_gmac-dwmac fe010000.ethernet: Can not read property: tx_delay.
> [ 7.365219] rk_gmac-dwmac fe010000.ethernet: set tx_delay to 0x30
> [ 7.365224] rk_gmac-dwmac fe010000.ethernet: Can not read property: rx_delay.
> [ 7.365228] rk_gmac-dwmac fe010000.ethernet: set rx_delay to 0x10

I've been meaning to make this a dev_debug message, because in the
various rgmii-id modes it is feasible for these to be non-existent in
the device-tree. In rgmii-id mode these are disabled, no matter what
they are set to in the dt.

>
> Signed-off-by: Anand Moon <linux.amoon@gmail.com>
> ---
> V2: Fix commit message and added the RX and TX clock delay.
> ---
> arch/arm64/boot/dts/rockchip/rk3568-rock-3a.dts | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/boot/dts/rockchip/rk3568-rock-3a.dts b/arch/arm64/boot/dts/rockchip/rk3568-rock-3a.dts
> index ea74ba32fbbd..e1c75532dcee 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3568-rock-3a.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3568-rock-3a.dts
> @@ -253,13 +253,16 @@ &gmac1 {
> assigned-clock-rates = <0>, <125000000>;
> clock_in_out = "output";
> phy-handle = <&rgmii_phy1>;
> - phy-mode = "rgmii-id";
> + phy-mode = "rgmii";
> pinctrl-names = "default";
> pinctrl-0 = <&gmac1m1_miim
> &gmac1m1_tx_bus2
> &gmac1m1_rx_bus2
> &gmac1m1_rgmii_clk
> &gmac1m1_rgmii_bus>;
> +
> + tx_delay = <0x4f>;
> + rx_delay = <0x26>;

These are pretty far off from the default, have you verified the upper
and lower bounds for the rock-3a? These should be roughly in the
middle of that range.

> status = "okay";
> };
>
> --
> 2.38.1
>