From: Andy Duan <fugang.duan@nxp.com>
To: Manfred Schlaegl <manfred.schlaegl@ginzinger.com>
CC: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] net: fec: hard phy reset on open
Thread-Topic: [PATCH] net: fec: hard phy reset on open
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Date: Mon, 24 Oct 2016 14:03:31 +0000
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From: manfred.schlaegl@gmx.at <manfred.schlaegl@gmx.at>  Sent: Monday, October 24, 2016 5:26 PM
> To: Andy Duan <fugang.duan@nxp.com>
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: [PATCH] net: fec: hard phy reset on open
> 
> We have seen some problems with auto negotiation on i.MX6 using LAN8720,
> after interface down/up.
> 
> In our configuration, the ptp clock is used externally as reference clock for
> the phy. Some phys (e.g. LAN8720) needs a stable clock while and after hard
> reset.
> Before this patch, the driver disabled the clock on close but did no hard reset
> on open, after enabling the clocks again.
> 
> A solution that prevents disabling the clocks on close was considered, but
> discarded because of bad power saving behavior.
> 
> This patch saves the reset dt properties on probe and does a reset on every
> open after clocks where enabled, to make sure the clock is stable while and
> after hard reset.
> 
> Tested on i.MX6 and i.MX28, both using LAN8720.
> 
> Signed-off-by: Manfred Schlaegl <manfred.schlaegl@ginzinger.com>
> ---
This patch did hard reset to let phy stable.
Firstly, you should do reset before clock enable.
Secondly, we suggest to do phy reset in phy driver, not MAC driver.

Regards,
Andy

>  drivers/net/ethernet/freescale/fec.h      |  4 ++
>  drivers/net/ethernet/freescale/fec_main.c | 77 +++++++++++++++++-------
> -------
>  2 files changed, 47 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/fec.h
> b/drivers/net/ethernet/freescale/fec.h
> index c865135..379e619 100644
> --- a/drivers/net/ethernet/freescale/fec.h
> +++ b/drivers/net/ethernet/freescale/fec.h
> @@ -498,6 +498,10 @@ struct fec_enet_private {
>  	struct clk *clk_enet_out;
>  	struct clk *clk_ptp;
> 
> +	int phy_reset;
> +	bool phy_reset_active_high;
> +	int phy_reset_msec;
> +
>  	bool ptp_clk_on;
>  	struct mutex ptp_clk_mutex;
>  	unsigned int num_tx_queues;
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c
> index 48a033e..8cc1ec5 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -2802,6 +2802,22 @@ static int fec_enet_alloc_buffers(struct
> net_device *ndev)
>  	return 0;
>  }
> 
> +static void fec_reset_phy(struct fec_enet_private *fep) {
> +	if (!gpio_is_valid(fep->phy_reset))
> +		return;
> +
> +	gpio_set_value_cansleep(fep->phy_reset, !!fep-
> >phy_reset_active_high);
> +
> +	if (fep->phy_reset_msec > 20)
> +		msleep(fep->phy_reset_msec);
> +	else
> +		usleep_range(fep->phy_reset_msec * 1000,
> +			     fep->phy_reset_msec * 1000 + 1000);
> +
> +	gpio_set_value_cansleep(fep->phy_reset, !fep-
> >phy_reset_active_high);
> +}
> +
>  static int
>  fec_enet_open(struct net_device *ndev)
>  {
> @@ -2817,6 +2833,8 @@ fec_enet_open(struct net_device *ndev)
>  	if (ret)
>  		goto clk_enable;
> 
> +	fec_reset_phy(fep);
> +
>  	/* I should reset the ring buffers here, but I don't yet know
>  	 * a simple way to do that.
>  	 */
> @@ -3183,52 +3201,39 @@ static int fec_enet_init(struct net_device *ndev)
>  	return 0;
>  }
> 
> -#ifdef CONFIG_OF
> -static void fec_reset_phy(struct platform_device *pdev)
> +static int
> +fec_get_reset_phy(struct platform_device *pdev, int *msec, int
> *phy_reset,
> +		  bool *active_high)
>  {
> -	int err, phy_reset;
> -	bool active_high = false;
> -	int msec = 1;
> +	int err;
>  	struct device_node *np = pdev->dev.of_node;
> 
> -	if (!np)
> -		return;
> +	if (!np || !of_device_is_available(np))
> +		return 0;
> 
> -	of_property_read_u32(np, "phy-reset-duration", &msec);
> +	of_property_read_u32(np, "phy-reset-duration", msec);
>  	/* A sane reset duration should not be longer than 1s */
> -	if (msec > 1000)
> -		msec = 1;
> +	if (*msec > 1000)
> +		*msec = 1;
> 
> -	phy_reset = of_get_named_gpio(np, "phy-reset-gpios", 0);
> -	if (!gpio_is_valid(phy_reset))
> -		return;
> +	*phy_reset = of_get_named_gpio(np, "phy-reset-gpios", 0);
> +	if (!gpio_is_valid(*phy_reset))
> +		return 0;
> 
> -	active_high = of_property_read_bool(np, "phy-reset-active-high");
> +	*active_high = of_property_read_bool(np, "phy-reset-active-high");
> 
> -	err = devm_gpio_request_one(&pdev->dev, phy_reset,
> -			active_high ? GPIOF_OUT_INIT_HIGH :
> GPIOF_OUT_INIT_LOW,
> -			"phy-reset");
> +	err = devm_gpio_request_one(&pdev->dev, *phy_reset,
> +				    *active_high ?
> +					GPIOF_OUT_INIT_HIGH :
> +					GPIOF_OUT_INIT_LOW,
> +				    "phy-reset");
>  	if (err) {
>  		dev_err(&pdev->dev, "failed to get phy-reset-gpios: %d\n",
> err);
> -		return;
> +		return err;
>  	}
> 
> -	if (msec > 20)
> -		msleep(msec);
> -	else
> -		usleep_range(msec * 1000, msec * 1000 + 1000);
> -
> -	gpio_set_value_cansleep(phy_reset, !active_high);
> -}
> -#else /* CONFIG_OF */
> -static void fec_reset_phy(struct platform_device *pdev) -{
> -	/*
> -	 * In case of platform probe, the reset has been done
> -	 * by machine code.
> -	 */
> +	return 0;
>  }
> -#endif /* CONFIG_OF */
> 
>  static void
>  fec_enet_get_queue_num(struct platform_device *pdev, int *num_tx, int
> *num_rx) @@ -3409,7 +3414,10 @@ fec_probe(struct platform_device
> *pdev)
>  	pm_runtime_set_active(&pdev->dev);
>  	pm_runtime_enable(&pdev->dev);
> 
> -	fec_reset_phy(pdev);
> +	ret = fec_get_reset_phy(pdev, &fep->phy_reset_msec, &fep-
> >phy_reset,
> +				&fep->phy_reset_active_high);
> +	if (ret)
> +		goto failed_reset;
> 
>  	if (fep->bufdesc_ex)
>  		fec_ptp_init(pdev);
> @@ -3467,6 +3475,7 @@ fec_probe(struct platform_device *pdev)
>  failed_mii_init:
>  failed_irq:
>  failed_init:
> +failed_reset:
>  	fec_ptp_stop(pdev);
>  	if (fep->reg_phy)
>  		regulator_disable(fep->reg_phy);
> --
> 2.1.4