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From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: "Pali Rohár" <pali@kernel.org>
Cc: Giammarco lynx <stich86@gmail.com>, linux-arm-kernel@lists.infradead.org
Subject: Re: Question abount VSOL/CarlitoxxPro SFP Patch on Marvell Armada (MCBIN DS)
Date: Mon, 9 May 2022 21:27:10 +0100	[thread overview]
Message-ID: <Ynl5HqqyZot375x6@shell.armlinux.org.uk> (raw)
In-Reply-To: <20220509170832.4wchp4tje2fvhpyh@pali>

On Mon, May 09, 2022 at 07:08:32PM +0200, Pali Rohár wrote:
> One GPON module which I tested, signals TX_FAULT when CPU tried to link
> at wrong speed. This is just my observation, nor sure if it is
> coincidence...
> 
> So when kernel set phylink to 2500base-x and GPON SFP module expected
> CPU to set phylink to 1000base-x then kernel received TX_FAULT. After I
> switched 2500base-x to 1000base-x TX_FAULT stopped and link started
> working.

If that's what that GPON module does, that's another invention by a
GPON SFP manufacturer.

> Btw, what does TX_FAULT signal means?

In the SFP MSA, an asserted TX_FAULT means that there is some kind of
laser fault with the module.

So, using TX_FAULT to signal "host, you got the interface speed wrong"
is very much some GPON module manufacturers invention.

> Yes, this sucks. Importance is that GPON ONU/ONT box (either in media
> box form factor or SFP form factor) is compliant to GPON standards and
> then that is also compliant to the vendor OMCI extension for correct
> provisioning from vendor OLT. For SFP the last importance is that it
> works in vendor's media box with SFP cage. And that is all. Nobody care
> about SFF standards compliance.
> 
> I do not know what we can done here. Maybe SFP subsystem should cycle
> between phy modes returned by sfp_parse_support() until one start
> working?
> 
> Dedicated GPON media boxes are in better shape because they have RJ45
> with copper ethernet over twisted pair and this has standardized
> autonegotiation of speed. So here if provisioning force speed 1Gbps then
> on LAN RJ45 port is mode changed to 1000base-t.

Maybe the right answer is we just stop trying to support GPON modules
with all their random manufacturer specific quirks and odd behaviours.

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

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  reply	other threads:[~2022-05-09 20:28 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAJbjdrQbAd01WmW-ZQ9d9QKAtUqbQcRkpadtfSH94o9ZUqkhAg@mail.gmail.com>
2022-03-07 16:18 ` Fwd: Question abount VSOL/CarlitoxxPro SFP Patch on Marvell Armada (MCBIN DS) Giammarco lynx
2022-03-07 17:13   ` Russell King (Oracle)
     [not found]     ` <CAJbjdrRiJMnQJEDCABOVxFyaqnSdBbq7Q-ixqBwW2ni49+gfgQ@mail.gmail.com>
     [not found]       ` <YiZZbskbuqq+I2PW@shell.armlinux.org.uk>
     [not found]         ` <CAJbjdrReN4B0XXFFLaTsPj_graAkguQPzP4xtRGbHeGozbJycQ@mail.gmail.com>
2022-03-07 20:12           ` Giammarco lynx
2022-03-07 23:01             ` Russell King (Oracle)
2022-03-08 10:08               ` Giammarco lynx
2022-03-08 11:15                 ` Russell King (Oracle)
2022-03-08 11:54                   ` Giammarco lynx
2022-03-08 12:12                     ` Russell King (Oracle)
     [not found]                       ` <CAJbjdrSRcGVavaWJHuO3_RnP8A30b_ZQS_yAUCUWKCqxrUMwLw@mail.gmail.com>
     [not found]                         ` <Yid39zuckqVLVJts@shell.armlinux.org.uk>
2022-03-08 15:51                           ` Giammarco lynx
2022-05-08 16:51                   ` Pali Rohár
2022-05-09 15:41                     ` Russell King (Oracle)
2022-05-09 17:08                       ` Pali Rohár
2022-05-09 20:27                         ` Russell King (Oracle) [this message]
2022-05-08 16:31               ` Pali Rohár
2022-05-09 11:13                 ` Giammarco lynx
2022-05-09 11:24                   ` Pali Rohár
     [not found]                 ` <dc809ba8-ec64-4ba7-a8e1-60c24bd30296@Spark>
2022-05-09 15:47                   ` Russell King (Oracle)
2022-05-08 16:38             ` Pali Rohár

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