netdev - Re: Correct method for initializing Pause and Asymmetrical Pause support in phy drivers

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Date:   Thu, 12 Jan 2017 16:52:38 +0100
From:   Zefir Kurtisi <zefir.kurtisi@...atec.com>
To:     Marc Bertola <marc.bertola@...lucid.ca>, netdev@...r.kernel.org
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Timur Tabi <timur@...eaurora.org>
Subject: Re: Correct method for initializing Pause and Asymmetrical Pause
 support in phy drivers

On 01/12/2017 04:21 PM, Marc Bertola wrote:
> Hello netdev list,
> 
> I am currently investigating a problem related to Ethernet
> auto-negotiation of Pause and Asymmetrical Pause capabilities.
> 
> TL;DR: I am using a Picozed system-on-module with a Xilinx Gigabit
> Ethernet MAC and a Marvell PHY. It does not appear to be advertising
> support for Pause and Asym Pause, which seems strange to me given that
> this is relatively recent hardware. I suspect that may be due to a
> problem in the way phydev->supported is initialized in
> drivers/net/phy/marvell.c.
> 
> I am trying to confirm what the proper method is to initialize
> phydev->supported such that it advertises SUPPORTED_Pause and
> SUPPORTED_Asym_Pause.  Adding these flags to (phy_driver).features
> seems to work, but I would like to confirm with people who are more
> knowledgeable than me in this regard.
> [...]

This was discussed only recently and iirc consensus was:
* flow control is an ETH property, PHY is only forwarding the info
* => therefore (Asym)Pause flags are to be set by ETH driver, not by PHY

For reference, Timur Tabi cleaned up the PHY drivers around two months ago in [1].


Cheers,
Zefir


[1] https://www.spinics.net/lists/netdev/msg403806.html