linux-kernel - Re: [PATCH net-master 1/1] net: phy: dp83867: Add speed optimization feature

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Message-ID: <01797864-5a63-c3a0-d1d2-99dfff3a0aa1@ti.com>
Date:   Fri, 31 Jan 2020 14:10:50 -0600
From:   Dan Murphy <dmurphy@...com>
To:     Florian Fainelli <f.fainelli@...il.com>, <andrew@...n.ch>,
        <hkallweit1@...il.com>, <bunk@...nel.org>
CC:     <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <grygorii.strashko@...com>
Subject: Re: [PATCH net-master 1/1] net: phy: dp83867: Add speed optimization
 feature

Florian

On 1/31/20 2:02 PM, Florian Fainelli wrote:
> On 1/31/20 11:54 AM, Dan Murphy wrote:
> <snip>
>> So then it would be ok to do a genphy_read_status and then override the
>> speed and duplex mode from the PHYSTS register?
> I would think so yes, especially if that is needed for reporting the
> actual link speed that ended up being negotiated, and not the one that
> the link was initially trained at. That assumes I understand that the
> problem is that you advertise and want Gigabit, but because of a 4-wire
> cable being plugged in, you ended up at 100Mbits/sec.

Exactly.

>> I don't think that the link change notification is needed.  The speed
>> should not change once the cable is plugged in and the speed is negotiated.
> The link change notification is just to signal to the user that the
> speed may have been reduced due to downshifting, which would/could
> happen with 4-wires instead of the expected 8-wires. Certainly not
> strictly necessary right now, I agree.

Ack

Dan