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Subject: Re: [Potential Spoof] Re: [PATCH net-next v6 3/3] net: phy: broadcom:
 add 1000Base-X support for BCM54616S
To:     Tao Ren <taoren@fb.com>, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S . Miller" <davem@davemloft.net>,
        Arun Parameswaran <arun.parameswaran@broadcom.com>,
        Justin Chen <justinpopo6@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>
References: <20190809054411.1015962-1-taoren@fb.com>
 <97cd059c-d98e-1392-c814-f3bd628e6366@gmail.com>
 <e556dd17-ef85-3c61-bc08-17db02d9a5dc@fb.com>
 <8f0e172b-575c-dab8-b695-c33dfc78fa8f@fb.com>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Message-ID: <d398ca57-575c-6e88-49a5-bf49cddfa2f0@gmail.com>
Date:   Fri, 9 Aug 2019 23:59:23 +0200
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On 09.08.2019 23:13, Tao Ren wrote:
> On 8/9/19 1:54 PM, Tao Ren wrote:
>> Hi Heiner,
>>
>> On 8/9/19 1:21 PM, Heiner Kallweit wrote:
>>> 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@fb.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?
>>
>> I'm doubting if 100Base-FX works. Besides auto-negotiation, 100Base-FX Control/Status registers are defined in shadow register instead of MII_BMCR and MII_BMSR.
>>
>> Unfortunately I don't have environment to test 100Base-FX and that's why I only make changes when the PHY is working in 1000X mode.
> 
> I can prepare a patch for 100Base-FX based on my understanding of bcm54616s datasheet, but the patch would be just compile-tested 
> 
Support for 1000Base-X should be sufficient. Best mention the missing support for
100Base-FX in the commit message and at a suited place in the driver code.

> 
> Thanks,
> 
> Tao
> 
Heiner