netdev - Re: [PATCH] [RFC] net: phy: phy drivers should not set SUPPORTED_Pause or SUPPORTED_Asym

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Message-ID: <582238F3.30906@codeaurora.org>
Date:   Tue, 8 Nov 2016 14:43:31 -0600
From:   Timur Tabi <timur@...eaurora.org>
To:     Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] [RFC] net: phy: phy drivers should not set
 SUPPORTED_Pause or SUPPORTED_Asym_Pause

On 11/07/2016 10:30 AM, Timur Tabi wrote:
>
> I'm still don't understand 100% how these flags really work, because I
> just can't shake the feeling that they should not be set for every phy.
>   If these flags are supposed to be turned on universally, then why are
> they even an option?

So I've been giving this more thought.  Can you tell me if the following 
is correct:

1) PHY drivers and/or phylib sets the SUPPORTED_Pause | 
SUPPORTED_AsymPause bits in phydev->supported.  This indicates that the 
PHY supports pause frames.

2) The MAC driver checks phydev->supported before it calls phy_start(). 
  If (SUPPORTED_Pause | SUPPORTED_AsymPause) is set, then it sets those 
bits in phydev->advertising if it wants to enable pause frame support.

3) When the link state changes, the MAC driver checks 
phydev->advertising, and if the bits are set, then it enables those 
features in the MAC.

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