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

[Tao Ren <taoren@fb.com>]

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 


Thanks,

Tao