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

From: "Arınç ÜNAL" <arinc.unal@arinc9.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: "Florian Fainelli" <f.fainelli@gmail.com>,
	"Daniel Golle" <daniel@makrotopia.org>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"DENG Qingfang" <dqfext@gmail.com>,
	"Sean Wang" <sean.wang@mediatek.com>,
	"Vladimir Oltean" <olteanv@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"AngeloGioacchino Del Regno"
	<angelogioacchino.delregno@collabora.com>,
	"René van Dorst" <opensource@vdorst.com>,
	"SkyLake Huang" <SkyLake.Huang@mediatek.com>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Bartel Eerdekens" <bartel.eerdekens@constell8.be>,
	mithat.guner@xeront.com, erkin.bozoglu@xeront.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH 0/3] Fix EEE support for MT7531 and MT7988 SoC switch
Date: Sun, 24 Mar 2024 14:45:11 +0300	[thread overview]
Message-ID: <6db6a339-e402-472f-b640-523ced553354@arinc9.com> (raw)
In-Reply-To: <ZgAQ4Ihsn6RCk7xx@shell.armlinux.org.uk>

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