netdev - Re: [PATCH net-next 2/2] net: phy: add phy_speed_down and phy_speed

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Message-ID: <1ddf575d-b894-e20c-b9af-016021eaf33e@gmail.com>
Date:   Thu, 12 Jul 2018 12:25:50 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Cc:     David Miller <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 2/2] net: phy: add phy_speed_down and
 phy_speed_up



On 07/12/2018 12:10 PM, Heiner Kallweit wrote:
> On 12.07.2018 21:09, Andrew Lunn wrote:
>>> Like r8169 also tg3 driver doesn't wait for the speed-down-renegotiation
>>> to finish. Therefore, even though I share Andrew's concerns, there seem
>>> to be chips where it's safe to not wait for the renegotiation to finish
>>> (e.g. because device is in PCI D3 already and can't generate an interrupt).
>>> Having said that I'd keep the sync parameter for phy_speed_down so that
>>> the driver can decide.
>>
>> Hi Heiner
>>
>> Please put a big fat comment about the dangers of sync=false in the
>> function header. We want people to known it is dangerous by default,
>> and should only be used in special conditions, when it is known to be
>> safe.
>> 	Andrew
>>
> OK ..

What part do you find dangerous? Magic Packets are UDP packets and they
are not routed (unless specifically taken care of) so there is already
some "lossy" behavior involved with waking-up an Ethernet MAC, I don't
think that is too bad to retry several times until the link comes up.
-- 
Florian