[PATCH V1] arm64: dts: imx8mp: fix FEC can't work when attached to generic phy driver

[Joakim Zhang]

Kindly pinging...

Best Regards,
Joakim Zhang

> -----Original Message-----
> From: Joakim Zhang <qiangqing.zhang at nxp.com>
> Sent: 2021年3月4日 19:40
> To: robh+dt at kernel.org; shawnguo at kernel.org; s.hauer at pengutronix.de;
> festevam at gmail.com
> Cc: kernel at pengutronix.de; dl-linux-imx <linux-imx at nxp.com>;
> devicetree at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> linux-kernel at vger.kernel.org
> Subject: [PATCH V1] arm64: dts: imx8mp: fix FEC can't work when attached to
> generic phy driver
> 
> Some users report that FEC can't work on i.MX8MP EVK board, it brings
> inconvenience. The root cause should be FEC controller attached to generic phy
> driver, as Realtek phy driver is built as module in the defconfig file
> (CONFIG_REALTEK_PHY=m), so it is unavailable. If provide "reset-gpios"
> property, it will reset phy when probed, and no way to re-config phy since we
> use the generic phy dirver, which leads FEC can't work.
> 
> There are two ways to let FEC work:
> 
> 1. If you want to use generic phy dirver, please delete "reset-gpios"
> property, keep power-on strapping pins configurations.
> 
> 2. If you want to use Realtek phy driver, please buildin driver
> (CONFIG_REALTEK_PHY=y), and had better add another two reset
> properties:
> 	reset-assert-us = <20000>;
> 	reset-deassert-us = <150000>;
> According to  RTL8211 serials PHY datasheet, for a complete PHY reset, reset
> pin must be asserted low for at least 10ms for internal regulator.
> Wait for at least 72ms (for internal circuits settling time) before accessing the
> PHY register.
> 
> This patch selects method 1, since users may waste time to find out FEC failure,
> in most cases, they just want to use networking to debug other modules.
> 
> Fixs: commit 9e847693c6f34 ("arm64: dts: freescale: Add i.MX8MP EVK board
> support")
> Signed-off-by: Joakim Zhang <qiangqing.zhang at nxp.com>
> ---
>  arch/arm64/boot/dts/freescale/imx8mp-evk.dts | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
> b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
> index 7db4273cc88b..4f5c2fb33eda 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
> @@ -97,7 +97,6 @@
>  			compatible = "ethernet-phy-ieee802.3-c22";
>  			reg = <1>;
>  			eee-broken-1000t;
> -			reset-gpios = <&gpio4 2 GPIO_ACTIVE_LOW>;
>  		};
>  	};
>  };
> --
> 2.17.1