netdev - Re: genphy_read_status() vs. 1000bT Pause capability

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Message-ID: <20170328010940.GG25549@lunn.ch>
Date:   Tue, 28 Mar 2017 03:09:40 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     netdev@...r.kernel.org
Subject: Re: genphy_read_status() vs. 1000bT Pause capability

On Tue, Mar 28, 2017 at 11:49:50AM +1100, Benjamin Herrenschmidt wrote:
> Hi !
> 
> I noticed that flow control isn't being enabled on a system I'm
> working on by default. I've tracked it down to two things:
> 
>  - The realtec.c PHY driver doesn't have Pause or Asym_Pause in
> its exposed capabilities. This is in part because PHY_GBIT_FEATURES
> does not include SUPPORTED_Pause and SUPPORTED_Asym_Pause. Is there
> a specific reason for that ?

Hi Ben

It is worth reading Documentation/networking/phy.txt

The MAC should set SUPPORTED_Pause and SUPPORTED_Asym_Pause if the MAC
supports these features. The PHY will then negotiate them.

	 Andrew