netdev - Re: [PATCH] net: phy: broadcom: force master mode for BCM54210E and B50212E

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Date:   Fri, 1 Sep 2017 17:22:24 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     Andrew Lunn <andrew@...n.ch>, Hauke Mehrtens <hauke@...ke-m.de>,
        bcm-kernel-feedback-list@...adcom.com,
        Rafał Miłecki <rafal@...ecki.pl>,
        andrew@...n.ch
Subject: Re: [PATCH] net: phy: broadcom: force master mode for BCM54210E and
 B50212E

On 09/01/2017 02:21 AM, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@...ecki.pl>
> 
> First of all let me explain that the code we use for BCM54210E is also
> executed for the B50212E. They are very similar so it probably makes
> sense but it may be worth noting. The IDs are:
> 0x600d84a1: BCM54210E (rev B0)
> 0x600d84a2: BCM54210E (rev B1)
> 0x600d84a5: B50212E (rev B0)
> 0x600d84a6: B50212E (rev B1)
> 
> I got a report that a board with BCM47189 SoC and B50212E B1 PHY doesn't
> work well with Intel's I217-LM and I218-LM:
> http://ark.intel.com/products/60019/Intel-Ethernet-Connection-I217-LM
> http://ark.intel.com/products/71307/Intel-Ethernet-Connection-I218-LM
> I was told there are massive ping loss.
> 
> A solution to this problem is setting master mode in the 1000BASE-T
> register. I noticed a similar fix is present in the tg3 driver. One
> thing I'm not sure if this is needed for BCM54210E. It shouldn't hurt
> however since both are so similar.
> 
> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
> ---
> David: I'm not 100% sure if this is the best fix, so let's give others
> (Florian?) a moment to look at it / review it, please.
> ---
>  drivers/net/phy/broadcom.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/phy/broadcom.c b/drivers/net/phy/broadcom.c
> index 1e9ad30a35c8..2569db0923b0 100644
> --- a/drivers/net/phy/broadcom.c
> +++ b/drivers/net/phy/broadcom.c
> @@ -43,6 +43,10 @@ static int bcm54210e_config_init(struct phy_device *phydev)
>  	val &= ~BCM54810_SHD_CLK_CTL_GTXCLK_EN;
>  	bcm_phy_write_shadow(phydev, BCM54810_SHD_CLK_CTL, val);
>  
> +	val = phy_read(phydev, MII_CTRL1000);
> +	val |= CTL1000_AS_MASTER | CTL1000_ENABLE_MASTER;
> +	phy_write(phydev, MII_CTRL1000, val);

So for both BCM54210E and BCM50212E, the default values are to have
CTL1000_AS_MASTER cleared, which means that the PHY is configured as a
slave, and CTRL1000_ENABLE_MASTER also clear, which means Automatic
Slave/Master configuration, which is a bit confusing.

I would be more comfortable if you introduced a new flag after
PHY_BRCM_DIS_TXCRXC_NOENRGY in order to configure these bits or not.
Your driver (bgmac I suppose?) could then set this flag at phy_connect()
time through phydev->dev_flags.

Chances are that you are not breaking other set ups, because I suspect
we might be the offender here but it might be better to limit that to
just the devices you have.
-- 
Florian