netdev - Re: [PATCH v2 net-next 02/10] net: phy: bcm7xx: Add jumbo frame configuration to PHY

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Date:   Wed, 25 Mar 2020 16:02:45 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        murali.policharla@...adcom.com
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Jiri Pirko <jiri@...nulli.us>,
        Ido Schimmel <idosch@...sch.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH v2 net-next 02/10] net: phy: bcm7xx: Add jumbo frame
 configuration to PHY



On 3/25/2020 3:45 PM, Vladimir Oltean wrote:
> On Wed, 25 Mar 2020 at 17:44, Heiner Kallweit <hkallweit1@...il.com> wrote:
>>
>> On 25.03.2020 16:22, Vladimir Oltean wrote:
>>> From: Murali Krishna Policharla <murali.policharla@...adcom.com>
>>>
>>> Add API to configure jumbo frame settings in PHY during initial PHY
>>> configuration.
>>>
>>> Signed-off-by: Murali Krishna Policharla <murali.policharla@...adcom.com>
>>> Reviewed-by: Scott Branden <scott.branden@...adcom.com>
>>> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
>>> ---
>>>  drivers/net/phy/bcm-phy-lib.c | 28 ++++++++++++++++++++++++++++
>>>  drivers/net/phy/bcm-phy-lib.h |  1 +
>>>  drivers/net/phy/bcm7xxx.c     |  4 ++++
>>>  include/linux/brcmphy.h       |  1 +
>>>  4 files changed, 34 insertions(+)
>>>
>>> diff --git a/drivers/net/phy/bcm-phy-lib.c b/drivers/net/phy/bcm-phy-lib.c
>>> index e0d3310957ff..a26c80e13b43 100644
>>> --- a/drivers/net/phy/bcm-phy-lib.c
>>> +++ b/drivers/net/phy/bcm-phy-lib.c
>>> @@ -423,6 +423,34 @@ int bcm_phy_28nm_a0b0_afe_config_init(struct phy_device *phydev)
>>>  }
>>>  EXPORT_SYMBOL_GPL(bcm_phy_28nm_a0b0_afe_config_init);
>>>
>>> +int bcm_phy_enable_jumbo(struct phy_device *phydev)
>>> +{
>>> +     int val = 0, ret = 0;
>>> +
>>> +     ret = phy_write(phydev, MII_BCM54XX_AUX_CTL,
>>> +                     MII_BCM54XX_AUXCTL_SHDWSEL_MISC);
>>> +     if (ret < 0)
>>> +             return ret;
>>> +
>>> +     val = phy_read(phydev, MII_BCM54XX_AUX_CTL);
>>> +
>>> +     /* Enable extended length packet reception */
>>> +     val |= MII_BCM54XX_AUXCTL_ACTL_EXT_PKT_LEN;
>>> +     ret = phy_write(phydev, MII_BCM54XX_AUX_CTL, val);
>>> +
>>
>> There are different helpers already in bcm-phy-lib,
>> e.g. bcm54xx_auxctl_read. Also bcm_phy_write_misc()
>> has has quite something in common with your new function.
>> It would be good if a helper could be used here.
>>
> 
> Thanks Heiner.
> I'm not quite sure the operation is performed correctly though? My
> books are telling me that the "Receive Extended Packet Length" field
> is accessible via the Auxiliary Control Register 0x18 when the shadow
> value is 000, not 111 as this patch is doing. At least for BCM54xxx in
> terms of which the macros are defined. Am I wrong?

I can confirm that for the BCM54810 PHY as well, the extended packet
length is in register 0x18 shadow 0b000.

Murali, which datsheet did you use as a reference? The internal document
for the 28nm EGPHY which is what this driver is supposed to drive is
also indicating the same thing.
-- 
Florian