netdev - Re: [PATCH net-next v3 2/2] net: phy: at803x: disable delay only for RGMII mode

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Message-ID: <1dddc455-309d-5e7d-ca26-479fe800a013@free.fr>
Date:   Tue, 19 Feb 2019 12:57:18 +0100
From:   Marc Gonzalez <marc.w.gonzalez@...e.fr>
To:     Vinod Koul <vkoul@...nel.org>,
        David S Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>
Cc:     MSM <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Niklas Cassel <niklas.cassel@...aro.org>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Nori Sekhar <nsekhar@...com>,
        Peter Ujfalusi <peter.ujfalusi@...com>
Subject: Re: [PATCH net-next v3 2/2] net: phy: at803x: disable delay only for
 RGMII mode

On 19/02/2019 07:18, Vinod Koul wrote:

> Per "Documentation/devicetree/bindings/net/ethernet.txt" RGMII mode
> should not have delay in PHY whereas RGMII_ID and RGMII_RXID/RGMII_TXID
> can have delay in phy.

PHY or phy? :-)

> So disable the delay only for RGMII mode and enable for other modes.
> Also treat the default case as disabled delays.
> 
> Fixes: cd28d1d6e52e: ("net: phy: at803x: Disable phy delay for RGMII mode")
> Reported-by: Peter Ujfalusi <peter.ujfalusi@...com>
> Reviewed-by: Niklas Cassel <niklas.cassel@...aro.org>
> Tested-by: Peter Ujfalusi <peter.ujflausi@...com>
> Signed-off-by: Vinod Koul <vkoul@...nel.org>
> ---
>  drivers/net/phy/at803x.c | 47 ++++++++++++++++++++++++++++++----------
>  1 file changed, 36 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> index c6e7d800fd7a..dc1b13f7fc12 100644
> --- a/drivers/net/phy/at803x.c
> +++ b/drivers/net/phy/at803x.c
> @@ -110,6 +110,18 @@ static int at803x_debug_reg_mask(struct phy_device *phydev, u16 reg,
>  	return phy_write(phydev, AT803X_DEBUG_DATA, val);
>  }
>  
> +static int at803x_enable_rx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0, 0,
> +				     AT803X_DEBUG_RX_CLK_DLY_EN);
> +}
> +
> +static int at803x_enable_tx_delay(struct phy_device *phydev)
> +{
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_5, 0,
> +				     AT803X_DEBUG_TX_CLK_DLY_EN);
> +}
> +
>  static int at803x_disable_rx_delay(struct phy_device *phydev)
>  {
>  	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
> @@ -255,23 +267,36 @@ static int at803x_config_init(struct phy_device *phydev)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> -		ret = at803x_disable_rx_delay(phydev);
> +	/* The hardware register default is RX and TX delay enabled, so lets
> +	 * first disable the RX and TX delays in phy and enable them based
> +	 * on the mode selected
> +	 */

"let's" (let us)

For the record, AFAIR, the default is not *quite* RX and TX enabled:

https://www.spinics.net/lists/netdev/msg444527.html

RX: enabled at HW reset
TX: disabled at HW reset, but retains value after SW reset

> +	ret = at803x_disable_rx_delay(phydev);
> +	if (ret < 0)
> +		return ret;
> +	ret = at803x_disable_tx_delay(phydev);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +	    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
> +		/* If RGMII_ID or RGMII_RXID are specified enable RX delay,
> +		 * otherwise keep it disabled
> +		 */
> +		ret = at803x_enable_rx_delay(phydev);
>  		if (ret < 0)
>  			return ret;
>  	}
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -			phydev->interface == PHY_INTERFACE_MODE_RGMII) {
> -		ret = at803x_disable_tx_delay(phydev);
> -		if (ret < 0)
> -			return ret;
> +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +	    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
> +		/* If RGMII_ID or RGMII_TXID are specified enable TX delay,
> +		 * otherwise keep it disabled
> +		 */
> +		ret = at803x_enable_tx_delay(phydev);
>  	}
>  
> -	return 0;
> +	return ret;
>  }

IMO, the asymmetry in error handling for RX and TX is unfortunate.

Didn't you like the way it was done in my old patch? :-)

https://www.spinics.net/lists/netdev/msg445053.html

Regards.