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Date:   Mon, 29 Aug 2022 14:30:29 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Divya.Koppera@microchip.com
Cc:     michael@walle.cc, o.rempel@pengutronix.de,
        UNGLinuxDriver@microchip.com, davem@davemloft.net,
        edumazet@google.com, hkallweit1@gmail.com, kuba@kernel.org,
        linux-kernel@vger.kernel.org, linux@armlinux.org.uk,
        netdev@vger.kernel.org, pabeni@redhat.com
Subject: Re: [PATCH net-next] net: phy: micrel: Adding SQI support for
 lan8814 phy
Message-ID: <YwyxZQrpuJo98yGk@lunn.ch>
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> Yes Channel 0 is correct.
> 
> > Again this is the first time I hear about SQI but it puzzles me that
> > it only evaluate one pair in this case. So as a user who reads this
> > SQI might be misleaded.
> > 
> 
> Yeah, It needs uAPI extension.

I think the current uAPI actually allows it, sort of. You can have
multiple instances of a netlink property in a netlink message.  So
simply add 2 or 4 ETHTOOL_A_LINKSTATE_SQI properties. The existing
user space tools will likely just print the first value it
finds. Newer versions can walk the messages and print them all.

The alternative is to add a new nest, like i did for cable test
results:

 +-+-------------------------------------------+--------+---------------------+
 | | ``ETHTOOL_A_CABLE_NEST_RESULT``           | nested | cable test result   |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number         |
 +-+-+-----------------------------------------+--------+---------------------+
 | | | ``ETHTOOL_A_CABLE_RESULTS_CODE``        | u8     | result code         |
 +-+-+-----------------------------------------+--------+---------------------+

You can then explicitly indicate which cable pair the SQI value
corresponds to. In order to keep backwards compatibility, you would
still need to provide ETHTOOL_A_LINKSTATE_SQI, and then additionally
have these nests.

     Andrew