Re: What is inside GPON SFP module? (Was: Re: Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts)

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Hauke Mehrtens <hauke@hauke-m.de>
Cc: "Pali Rohár" <pali@kernel.org>,
	"Vladimir Oltean" <olteanv@gmail.com>,
	"Madalin Bucur" <madalin.bucur@nxp.com>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Igal Liberman" <Igal.Liberman@freescale.com>,
	"Shruti Kanetkar" <Shruti@freescale.com>,
	"Emil Medve" <Emilian.Medve@freescale.com>,
	"Scott Wood" <oss@buserror.net>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Camelia Alexandra Groza (OSS)" <camelia.groza@oss.nxp.com>
Subject: Re: What is inside GPON SFP module? (Was: Re: Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts)
Date: Sat, 5 Jun 2021 15:41:05 +0100	[thread overview]
Message-ID: <20210605144105.GZ30436@shell.armlinux.org.uk> (raw)
In-Reply-To: <80966478-8a7c-b66f-50b7-e50fc00b1784@hauke-m.de>

On Sat, Jun 05, 2021 at 03:04:55PM +0200, Hauke Mehrtens wrote:
> Is there a list of things these GPON sticks running Linux should do better
> in the future? For example what to avoid in the EEPROM emulation handling?

That is just not worth persuing. Large ISP-companies who have plenty of
buying power have tried to get issues with GPON sticks resolved, and the
response from the GPON stick manufacturers has not been helpful. I had
contracted with a national telco over this problem in recent years, and
I know they tried their best.

If large ISP companies who are significant customers can't effect any
fixes, you can be absolutely sure that the voluntary effort around the
Linux kernel will have no effect.

Yes, we list the modules that don't work well in the kernel source, and
sometimes we name and shame them, but they don't care.

For example, there is are a few modules that take up to 60 seconds
before they respond to any I2C requests, because the I2C is entirely
emulated by the Linux kernel running on the stick, and it takes that
long for the stick to boot. Will that ever get fixed? Probably not
without a hardware redesign. Will that happen? I really doubt it, and
eevn if it did it doesn't affect the millions of sticks already out
there.

IMHO trying to get these issues fixed is pie in the sky.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!