netdev - Re: [PATCH 0/3] Fix EEE support for MT7531 and MT7988 SoC switch

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Date: Sun, 24 Mar 2024 14:45:11 +0300
From: Arınç ÜNAL <arinc.unal@...nc9.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Florian Fainelli <f.fainelli@...il.com>,
 Daniel Golle <daniel@...rotopia.org>, Andrew Lunn <andrew@...n.ch>,
 DENG Qingfang <dqfext@...il.com>, Sean Wang <sean.wang@...iatek.com>,
 Vladimir Oltean <olteanv@...il.com>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 René van Dorst <opensource@...rst.com>,
 SkyLake Huang <SkyLake.Huang@...iatek.com>,
 Heiner Kallweit <hkallweit1@...il.com>,
 Bartel Eerdekens <bartel.eerdekens@...stell8.be>, mithat.guner@...ont.com,
 erkin.bozoglu@...ont.com, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 0/3] Fix EEE support for MT7531 and MT7988 SoC switch

On 24.03.2024 14:39, Russell King (Oracle) wrote:
> On Sun, Mar 24, 2024 at 12:47:08PM +0300, Arınç ÜNAL wrote:
>> I've tested with switch ports interfaces' tx-timer from 0 to 40, same
>> tx-timer for both interfaces. Loss is still there.
> 
> EEE implementations tend to be a mess in the way drivers implement the
> API, so one can't at the moment rely on what ethtool says about the
> status. Sadly, this is what happens when driver authors are left to
> their own ends. :(
> 
>> I suppose the MT7531 switch PHYs need calibration for EEE that is currently
>> missing from the mediatek-ge driver.
> 
> EEE is quite simple from the software point of view. There is software
> negotiation of the modules that EEE supports, and then there is are
> one or more timers that affect the behaviour of EEE. The LPI timer is
> "how long the link needs to be idle for before _this_ end signals that
> it _can_ enter low power state". The link only enters low power state
> when *both* ends of the link signal that they can enter low power
> state.
> 
> What calibration would be necessary?

Check out mt798x_phy_eee() on drivers/net/phy/mediatek-ge-soc.c.

Arınç