linux-kernel - Re: [PATCH v1] ARM: dts: aspeed: ast2600-evb: Enable RX delay for MAC0/MAC1

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Date:   Fri, 18 Mar 2022 08:46:28 +0000
From:   Joel Stanley <joel@....id.au>
To:     Howard Chiu <howard_chiu@...eedtech.com>
Cc:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "andrew@...id.au" <andrew@...id.au>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Troy Lee <troy_lee@...eedtech.com>
Subject: Re: [PATCH v1] ARM: dts: aspeed: ast2600-evb: Enable RX delay for MAC0/MAC1

Hi Howard,

On Fri, 18 Mar 2022 at 08:09, Howard Chiu <howard_chiu@...eedtech.com> wrote:
>
> Since mac0/1 and mac2/3 are physically located on different die,
> they have different properties by nature, which is mac0/1 has smaller delay step.
>
> The property 'phy-mode' on ast2600 mac0 and mac1 is recommended to set to 'rgmii-rxid'
> which enables the RX interface delay from the PHY chip.
> Refer page 45 of SDK User Guide v08.00
> https://github.com/AspeedTech-BMC/openbmc/releases/download/v08.00/SDK_User_Guide_v08.00.pdf
>
> Set mac delay according to the mactest result.

This bit confused me. How does the rxid relate to the mac delay
numbers? Which device and code is responsible for using them?

>
> Signed-off-by: Howard Chiu <howard_chiu@...eedtech.com>
> ---
>  arch/arm/boot/dts/aspeed-ast2600-evb.dts | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/boot/dts/aspeed-ast2600-evb.dts b/arch/arm/boot/dts/aspeed-ast2600-evb.dts
> index b7eb552640cb..db16ba307e97 100644
> --- a/arch/arm/boot/dts/aspeed-ast2600-evb.dts
> +++ b/arch/arm/boot/dts/aspeed-ast2600-evb.dts
> @@ -103,7 +103,7 @@ ethphy3: ethernet-phy@0 {
>  &mac0 {
>         status = "okay";
>
> -       phy-mode = "rgmii";
> +       phy-mode = "rgmii-rxid";
>         phy-handle = <&ethphy0>;
>
>         pinctrl-names = "default";
> @@ -114,7 +114,7 @@ &mac0 {
>  &mac1 {
>         status = "okay";
>
> -       phy-mode = "rgmii";
> +       phy-mode = "rgmii-rxid";
>         phy-handle = <&ethphy1>;
>
>         pinctrl-names = "default";
> @@ -141,6 +141,21 @@ &mac3 {
>         pinctrl-0 = <&pinctrl_rgmii4_default>;
>  };
>
> +&syscon {
> +       mac0-clk-delay = <0x10 0x0a
> +                         0x10 0x10
> +                         0x10 0x10>;

These properties aren't supported by the mainline kernel. Do you have
some code coming for that support?

> +       mac1-clk-delay = <0x10 0x0a
> +                         0x10 0x10
> +                         0x10 0x10>;
> +       mac2-clk-delay = <0x08 0x04
> +                         0x08 0x04
> +                         0x08 0x04>;
> +       mac3-clk-delay = <0x08 0x04
> +                         0x08 0x04
> +                         0x08 0x04>;
> +};
> +
>  &emmc_controller {
>         status = "okay";
>  };
> --
> 2.25.1
>