linux-kernel - Re: [PATCH net-next v2 7/7] net: phy: microchip_t1s: configure collision detection based on PLCA mode

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Message-ID: <20240903064312.2vsoqkoiiuaywg3w@DEN-DL-M31836.microchip.com>
Date: Tue, 3 Sep 2024 08:43:12 +0200
From: Horatiu Vultur <horatiu.vultur@...rochip.com>
To: Parthiban Veerasooran <Parthiban.Veerasooran@...rochip.com>
CC: <andrew@...n.ch>, <hkallweit1@...il.com>, <linux@...linux.org.uk>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <ramon.nordin.rodriguez@...roamp.se>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<UNGLinuxDriver@...rochip.com>, <Thorsten.Kummermehr@...rochip.com>
Subject: Re: [PATCH net-next v2 7/7] net: phy: microchip_t1s: configure
 collision detection based on PLCA mode

The 09/02/2024 20:04, Parthiban Veerasooran wrote:

Hi Parthiban,

> As per LAN8650/1 Rev.B0/B1 AN1760 (Revision F (DS60001760G - June 2024))
> and LAN8670/1/2 Rev.C1/C2 AN1699 (Revision E (DS60001699F - June 2024)),
> under normal operation, the device should be operated in PLCA mode.
> Disabling collision detection is recommended to allow the device to
> operate in noisy environments or when reflections and other inherent
> transmission line distortion cause poor signal quality. Collision
> detection must be re-enabled if the device is configured to operate in
> CSMA/CD mode.

Is this something that applies only to Microchip PHYs or is something
generic that applies to all the PHYs.

> 
> Signed-off-by: Parthiban Veerasooran <Parthiban.Veerasooran@...rochip.com>
> ---
>  drivers/net/phy/microchip_t1s.c | 42 ++++++++++++++++++++++++++++++---
>  1 file changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/phy/microchip_t1s.c b/drivers/net/phy/microchip_t1s.c
> index bd0c768df0af..a0565508d7d2 100644
> --- a/drivers/net/phy/microchip_t1s.c
> +++ b/drivers/net/phy/microchip_t1s.c
> @@ -26,6 +26,12 @@
>  #define LAN865X_REG_CFGPARAM_CTRL 0x00DA
>  #define LAN865X_REG_STS2 0x0019
>  
> +/* Collision Detector Control 0 Register */
> +#define LAN86XX_REG_COL_DET_CTRL0	0x0087
> +#define COL_DET_CTRL0_ENABLE_BIT_MASK	BIT(15)
> +#define COL_DET_ENABLE			BIT(15)
> +#define COL_DET_DISABLE			0x0000
> +
>  #define LAN865X_CFGPARAM_READ_ENABLE BIT(1)
>  
>  /* The arrays below are pulled from the following table from AN1699
> @@ -370,6 +376,36 @@ static int lan867x_revb1_config_init(struct phy_device *phydev)
>  	return 0;
>  }
>  
> +/* As per LAN8650/1 Rev.B0/B1 AN1760 (Revision F (DS60001760G - June 2024)) and
> + * LAN8670/1/2 Rev.C1/C2 AN1699 (Revision E (DS60001699F - June 2024)), under
> + * normal operation, the device should be operated in PLCA mode. Disabling
> + * collision detection is recommended to allow the device to operate in noisy
> + * environments or when reflections and other inherent transmission line
> + * distortion cause poor signal quality. Collision detection must be re-enabled
> + * if the device is configured to operate in CSMA/CD mode.
> + *
> + * AN1760: https://www.microchip.com/en-us/application-notes/an1760
> + * AN1699: https://www.microchip.com/en-us/application-notes/an1699
> + */
> +static int lan86xx_plca_set_cfg(struct phy_device *phydev,
> +				const struct phy_plca_cfg *plca_cfg)
> +{
> +	int ret;
> +
> +	ret = genphy_c45_plca_set_cfg(phydev, plca_cfg);
> +	if (ret)
> +		return ret;
> +
> +	if (plca_cfg->enabled)
> +		return phy_modify_mmd(phydev, MDIO_MMD_VEND2,
> +				      LAN86XX_REG_COL_DET_CTRL0,
> +				      COL_DET_CTRL0_ENABLE_BIT_MASK,
> +				      COL_DET_DISABLE);
> +
> +	return phy_modify_mmd(phydev, MDIO_MMD_VEND2, LAN86XX_REG_COL_DET_CTRL0,
> +			      COL_DET_CTRL0_ENABLE_BIT_MASK, COL_DET_ENABLE);
> +}
> +
>  static int lan86xx_read_status(struct phy_device *phydev)
>  {
>  	/* The phy has some limitations, namely:
> @@ -403,7 +439,7 @@ static struct phy_driver microchip_t1s_driver[] = {
>  		.config_init        = lan867x_revc_config_init,
>  		.read_status        = lan86xx_read_status,
>  		.get_plca_cfg	    = genphy_c45_plca_get_cfg,
> -		.set_plca_cfg	    = genphy_c45_plca_set_cfg,
> +		.set_plca_cfg	    = lan86xx_plca_set_cfg,
>  		.get_plca_status    = genphy_c45_plca_get_status,
>  	},
>  	{
> @@ -413,7 +449,7 @@ static struct phy_driver microchip_t1s_driver[] = {
>  		.config_init        = lan867x_revc_config_init,
>  		.read_status        = lan86xx_read_status,
>  		.get_plca_cfg	    = genphy_c45_plca_get_cfg,
> -		.set_plca_cfg	    = genphy_c45_plca_set_cfg,
> +		.set_plca_cfg	    = lan86xx_plca_set_cfg,
>  		.get_plca_status    = genphy_c45_plca_get_status,
>  	},
>  	{
> @@ -423,7 +459,7 @@ static struct phy_driver microchip_t1s_driver[] = {
>  		.config_init        = lan865x_revb_config_init,
>  		.read_status        = lan86xx_read_status,
>  		.get_plca_cfg	    = genphy_c45_plca_get_cfg,
> -		.set_plca_cfg	    = genphy_c45_plca_set_cfg,
> +		.set_plca_cfg	    = lan86xx_plca_set_cfg,
>  		.get_plca_status    = genphy_c45_plca_get_status,
>  	},
>  };
> -- 
> 2.34.1
> 

-- 
/Horatiu