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

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Date:   Wed, 9 Nov 2016 11:34:02 -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 11/09/2016 11:06 AM, Florian Fainelli wrote:

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

So I'm still not sure *where* phylib should set the bits in 
phydev->supported.  I previously thought that phy_sanitize_settings() 
would be a candidate, but that function is called only when 
autonegotiation is disabled.

So the only thing I can think of is to do this:

/* A mapping of all SUPPORTED settings to speed/duplex */
static const struct phy_setting settings[] = {
	{
		.speed = SPEED_10000,
		.duplex = DUPLEX_FULL,
-		.setting = SUPPORTED_10000baseKR_Full,
+		.setting = SUPPORTED_10000baseKR_Full |
+			SUPPORTED_Pause | SUPPORTED_Asym_Pause,

... for all of the entries in settings[]

But this seems excessive, and I don't know if all of these SPEED_xxx 
standards actually support pause frames.

 >> >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.

> Almost, we need to see what the link partner advertised, by looking at
> phydev->pause / phydev->asym_pause and checking the local knobs whether
> flow control can be enabled, but other than that, this looks correct to me.

Yes, that's what I meant to write.  Fortunately, my EMAC driver already 
does this.

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