linux-kernel - Re: [PATCH] arm64: dts: meson: fix PHY deassert timing requirements

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Message-ID: <1j8sai7wr0.fsf@starbuckisacylon.baylibre.com>
Date:   Tue, 01 Dec 2020 09:31:47 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Stefan Agner <stefan@...er.ch>, robh+dt@...nel.org,
        khilman@...libre.com
Cc:     narmstrong@...libre.com, martin.blumenstingl@...glemail.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: meson: fix PHY deassert timing requirements


On Tue 01 Dec 2020 at 01:25, Stefan Agner <stefan@...er.ch> wrote:

> According to the datasheet (Rev. 1.4, page 30) the RTL8211F requires
> at least 50ms "for internal circuits settling time" before accessing
> the PHY registers. This fixes an issue where the Ethernet link doesn't
> come up when using ip link set down/up:
>   [   29.360965] meson8b-dwmac ff3f0000.ethernet eth0: Link is Down
>   [   34.569012] meson8b-dwmac ff3f0000.ethernet eth0: PHY [0.0:00] driver [RTL8211F Gigabit Ethernet] (irq=31)
>   [   34.676732] meson8b-dwmac ff3f0000.ethernet: Failed to reset the dma
>   [   34.678874] meson8b-dwmac ff3f0000.ethernet eth0: stmmac_hw_setup: DMA engine initialization failed
>   [   34.687850] meson8b-dwmac ff3f0000.ethernet eth0: stmmac_open: Hw setup failed
>
> Fixes: 658e4129bb81 ("arm64: dts: meson: g12b: odroid-n2: add the Ethernet PHY reset line")
> Signed-off-by: Stefan Agner <stefan@...er.ch>
> ---
>  arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dtsi | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dtsi b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dtsi
> index 6982632ae646..a5652caacb27 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dtsi
> @@ -413,7 +413,7 @@ external_phy: ethernet-phy@0 {
>  		max-speed = <1000>;
>  
>  		reset-assert-us = <10000>;
> -		reset-deassert-us = <30000>;
> +		reset-deassert-us = <50000>;
>  		reset-gpios = <&gpio GPIOZ_15 (GPIO_ACTIVE_LOW | GPIO_OPEN_DRAIN)>;
>  
>  		interrupt-parent = <&gpio_intc>;

Thanks for sharing this is Stefan,
The title of your patch should probably be modified to show that it
addresses the odroid n2 only, as it stands.

I have checked the RTL8211F doc I have, v1.9, and this one mention
"72ms at least - not including the 1.0V supply rise time" before
accessing the PHY registers :/ ... so 80ms maybe ?