linux-kernel - Re: [PATCH net-next v6 3/3] net: phy: broadcom: add 1000Base-X support for BCM54616S

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Message-ID: <97cd059c-d98e-1392-c814-f3bd628e6366@gmail.com>
Date:   Fri, 9 Aug 2019 22:21:31 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Tao Ren <taoren@...com>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Arun Parameswaran <arun.parameswaran@...adcom.com>,
        Justin Chen <justinpopo6@...il.com>,
        Vladimir Oltean <olteanv@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org
Subject: Re: [PATCH net-next v6 3/3] net: phy: broadcom: add 1000Base-X
 support for BCM54616S

On 09.08.2019 07:44, Tao Ren wrote:
> The BCM54616S PHY cannot work properly in RGMII->1000Base-KX mode (for
> example, on Facebook CMM BMC platform), mainly because genphy functions
> are designed for copper links, and 1000Base-X (clause 37) auto negotiation
> needs to be handled differently.
> 
> This patch enables 1000Base-X support for BCM54616S by customizing 3
> driver callbacks:
> 
>   - probe: probe callback detects PHY's operation mode based on
>     INTERF_SEL[1:0] pins and 1000X/100FX selection bit in SerDES 100-FX
>     Control register.
> 
>   - config_aneg: calls genphy_c37_config_aneg when the PHY is running in
>     1000Base-X mode; otherwise, genphy_config_aneg will be called.
> 
>   - read_status: calls genphy_c37_read_status when the PHY is running in
>     1000Base-X mode; otherwise, genphy_read_status will be called.
> 
> Signed-off-by: Tao Ren <taoren@...com>
> ---
>  Changes in v6:
>   - nothing changed.
>  Changes in v5:
>   - include Heiner's patch "net: phy: add support for clause 37
>     auto-negotiation" into the series.
>   - use genphy_c37_config_aneg and genphy_c37_read_status in BCM54616S
>     PHY driver's callback when the PHY is running in 1000Base-X mode.
>  Changes in v4:
>   - add bcm54616s_config_aneg_1000bx() to deal with auto negotiation in
>     1000Base-X mode.
>  Changes in v3:
>   - rename bcm5482_read_status to bcm54xx_read_status so the callback can
>     be shared by BCM5482 and BCM54616S.
>  Changes in v2:
>   - Auto-detect PHY operation mode instead of passing DT node.
>   - move PHY mode auto-detect logic from config_init to probe callback.
>   - only set speed (not including duplex) in read_status callback.
>   - update patch description with more background to avoid confusion.
>   - patch #1 in the series ("net: phy: broadcom: set features explicitly
>     for BCM54616") is dropped: the fix should go to get_features callback
>     which may potentially depend on this patch.
> 
>  drivers/net/phy/broadcom.c | 54 +++++++++++++++++++++++++++++++++++---
>  include/linux/brcmphy.h    | 10 +++++--
>  2 files changed, 58 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/phy/broadcom.c b/drivers/net/phy/broadcom.c
> index 937d0059e8ac..fbd76a31c142 100644
> --- a/drivers/net/phy/broadcom.c
> +++ b/drivers/net/phy/broadcom.c
> @@ -383,9 +383,9 @@ static int bcm5482_config_init(struct phy_device *phydev)
>  		/*
>  		 * Select 1000BASE-X register set (primary SerDes)
>  		 */
> -		reg = bcm_phy_read_shadow(phydev, BCM5482_SHD_MODE);
> -		bcm_phy_write_shadow(phydev, BCM5482_SHD_MODE,
> -				     reg | BCM5482_SHD_MODE_1000BX);
> +		reg = bcm_phy_read_shadow(phydev, BCM54XX_SHD_MODE);
> +		bcm_phy_write_shadow(phydev, BCM54XX_SHD_MODE,
> +				     reg | BCM54XX_SHD_MODE_1000BX);
>  
>  		/*
>  		 * LED1=ACTIVITYLED, LED3=LINKSPD[2]
> @@ -451,12 +451,44 @@ static int bcm5481_config_aneg(struct phy_device *phydev)
>  	return ret;
>  }
>  
> +static int bcm54616s_probe(struct phy_device *phydev)
> +{
> +	int val, intf_sel;
> +
> +	val = bcm_phy_read_shadow(phydev, BCM54XX_SHD_MODE);
> +	if (val < 0)
> +		return val;
> +
> +	/* The PHY is strapped in RGMII to fiber mode when INTERF_SEL[1:0]
> +	 * is 01b.
> +	 */
> +	intf_sel = (val & BCM54XX_SHD_INTF_SEL_MASK) >> 1;
> +	if (intf_sel == 1) {
> +		val = bcm_phy_read_shadow(phydev, BCM54616S_SHD_100FX_CTRL);
> +		if (val < 0)
> +			return val;
> +
> +		/* Bit 0 of the SerDes 100-FX Control register, when set
> +		 * to 1, sets the MII/RGMII -> 100BASE-FX configuration.
> +		 * When this bit is set to 0, it sets the GMII/RGMII ->
> +		 * 1000BASE-X configuration.
> +		 */
> +		if (!(val & BCM54616S_100FX_MODE))
> +			phydev->dev_flags |= PHY_BCM_FLAGS_MODE_1000BX;
> +	}
> +
> +	return 0;
> +}
> +
>  static int bcm54616s_config_aneg(struct phy_device *phydev)
>  {
>  	int ret;
>  
>  	/* Aneg firsly. */
> -	ret = genphy_config_aneg(phydev);
> +	if (phydev->dev_flags & PHY_BCM_FLAGS_MODE_1000BX)
> +		ret = genphy_c37_config_aneg(phydev);
> +	else
> +		ret = genphy_config_aneg(phydev);
>  

I'm just wondering whether it needs to be considered that 100base-FX
doesn't support auto-negotiation. I suppose BMSR reports aneg as
supported, therefore phylib will use aneg per default.
Not sure who could set 100Base-FX mode when, but maybe at that place
also phydev->autoneg needs to be cleared. Did you test 100Base-FX mode?

Heiner