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

From: Florian Fainelli <f.fainelli@gmail.com>
To: Daniel Golle <daniel@makrotopia.org>, Andrew Lunn <andrew@lunn.ch>
Cc: "Arınç ÜNAL" <arinc.unal@arinc9.com>,
	"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>,
	"Russell King" <linux@armlinux.org.uk>,
	"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: Tue, 19 Mar 2024 14:31:25 -0700	[thread overview]
Message-ID: <38798882-c033-4949-9446-4c6f15c25ebe@gmail.com> (raw)
In-Reply-To: <Zfn1DxkEa3u-f7l2@makrotopia.org>

On 3/19/24 13:26, Daniel Golle wrote:
> On Tue, Mar 19, 2024 at 08:38:03PM +0100, Andrew Lunn wrote:
>>> I would argue that EEE advertisement on the PHY should be enabled by
>>> default.
>>
>> That is an open question at the moment. For some use cases, it can add
>> extra delay and jitter which can cause problems. I've heard people
>> doing PTP don't like EEE for example.
> 
> MediaTek consumer-grade hardware doesn't support PTP and hence that
> quite certainly won't ever be an issue with all switch ICs supported
> by the mt7530 driver.
> 
> I'd rather first change the (configuration) default in OpenWrt (which
> is arguable the way most people are using this hardware), also because
> that will be more visible/obvious for users. Or even just make EEE
> configurable in the LuCI web-UI as a first step so users start playing
> with it.
> 
> After all, I also have a hard time imagining that MediaTek disabled
> EEE in their downstream driver for no reason:
> 
> https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/24091177a18ba7f2dd8d928a8f5b27b14df46b16

EEE tends to be an interoperability trap and typically results in 
unexplained link drops with different link partners which are difficult 
to debug and root cause. It would be great to have more context as to 
why it was disabled in the downstream tree to know what we are up 
against, though I would not be surprised if there had been a number of 
issues reported.

That said as an user, if someone has a well controlled environment, they 
should absolutely be able to turn on EEE and see how stable it holds in 
their environment.
-- 
Florian