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

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Message-ID: <CAMdYzYrgtzeP2OL2Vw0pDHQuJDhRbUy3X4xq9+XchgTGB9dqpg@mail.gmail.com>
Date:   Wed, 16 Nov 2022 15:36:24 -0500
From:   Peter Geis <pgwipeout@...il.com>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Chukun Pan <amadeus@....edu.cn>,
        Michael Riesch <michael.riesch@...fvision.net>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [linux-next-v2 1/5] arm64: dts: rockchip: Fix gmac phy mode to
 rgmii on Rock 3A SBC.

On Wed, Nov 16, 2022 at 3:02 PM Anand Moon <linux.amoon@...il.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@...il.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
>