netdev - RE: [EXT] [PATCH v1] net: fec: optionally reset PHY via a reset-controller

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Message-ID: <VI1PR0402MB36009E99D7361583702B84DDFFCE0@VI1PR0402MB3600.eurprd04.prod.outlook.com>
Date:   Tue, 16 Jul 2019 02:02:05 +0000
From:   Andy Duan <fugang.duan@....com>
To:     Sven Van Asbroeck <thesven73@...il.com>
CC:     "David S . Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [EXT] [PATCH v1] net: fec: optionally reset PHY via a
 reset-controller

From: Sven Van Asbroeck <thesven73@...il.com> Sent: Tuesday, July 16, 2019 5:05 AM
> The current fec driver allows the PHY to be reset via a gpio, specified in the
> devicetree. However, some PHYs need to be reset in a more complex way.
> 
> To accommodate such PHYs, allow an optional reset controller in the fec
> devicetree. If no reset controller is found, the fec will fall back to the legacy
> reset behaviour.
> 
> Example:
> &fec {
>         phy-mode = "rgmii";
>         resets = <&phy_reset>;
>         reset-names = "phy";
>         status = "okay";
> };
> 
> Signed-off-by: Sven Van Asbroeck <TheSven73@...il.com>
> ---
> 
> Will send a Documentation patch if this receives a positive review.
> 
>  drivers/net/ethernet/freescale/fec_main.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c
> index 38f10f7dcbc3..5a5f3ed6f16d 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -61,6 +61,7 @@
>  #include <linux/regulator/consumer.h>
>  #include <linux/if_vlan.h>
>  #include <linux/pinctrl/consumer.h>
> +#include <linux/reset.h>
>  #include <linux/prefetch.h>
>  #include <soc/imx/cpuidle.h>
> 
> @@ -3335,6 +3336,7 @@ static int fec_enet_get_irq_cnt(struct
> platform_device *pdev)  static int  fec_probe(struct platform_device *pdev)
> {
> +       struct reset_control *phy_reset;
>         struct fec_enet_private *fep;
>         struct fec_platform_data *pdata;
>         struct net_device *ndev;
> @@ -3490,7 +3492,9 @@ fec_probe(struct platform_device *pdev)
>         pm_runtime_set_active(&pdev->dev);
>         pm_runtime_enable(&pdev->dev);
> 
> -       ret = fec_reset_phy(pdev);
> +       phy_reset = devm_reset_control_get_exclusive(&pdev->dev,
> "phy");
> +       ret = IS_ERR(phy_reset) ? fec_reset_phy(pdev) :
> +                       reset_control_reset(phy_reset);
>         if (ret)
>                 goto failed_reset;

The patch looks fine.
But the reset mechanism in the driver should be abandoned since
the phylib already can handle mii bus reset and phy device reset like
below piece code:

of_mdiobus_register()
    of_mdiobus_register_phy()
        phy_device_register()
            mdiobus_register_device()
                /* Assert the reset signal */
                mdio_device_reset(mdiodev, 1);
            /* Deassert the reset signal */
            mdio_device_reset(&phydev->mdio, 0);

dts:
        ethernet-phy@0 {
            compatible = "ethernet-phy-id0141.0e90", "ethernet-phy-ieee802.3-c45";
            interrupt-parent = <&PIC>;
            interrupts = <35 1>;
            reg = <0>;

            resets = <&rst 8>;
            reset-names = "phy";
            reset-gpios = <&gpio1 4 1>;
            reset-assert-us = <1000>;
            reset-deassert-us = <2000>;
        };
    };
            
Please refer to doc:
Documentation/devicetree/bindings/net/ethernet-phy.yaml
> 
> --
> 2.17.1