netdev - RE: Marvell phy errata origins?

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Date:   Tue, 18 Apr 2017 15:09:46 +0000
From:   Harini Katakam <harini.katakam@...inx.com>
To:     Daniel Walker <danielwa@...co.com>, Andrew Lunn <andrew@...n.ch>
CC:     Florian Fainelli <f.fainelli@...il.com>,
        Andy Fleming <afleming@...escale.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        HEMANT RAMDASI <hramdasi@...co.com>,
        "Julius Hemanth Pitti -X (jpitti - MONTA VISTA SOFTWARE INC at Cisco)" 
        <jpitti@...co.com>,
        "harinikatakamlinux@...il.com" <harinikatakamlinux@...il.com>
Subject: RE: Marvell phy errata origins?

Hi Daniel,

> -----Original Message-----
> From: Daniel Walker [mailto:danielwa@...co.com]
> Sent: Tuesday, April 18, 2017 8:26 PM
> To: Harini Katakam <harinik@...inx.com>; Andrew Lunn <andrew@...n.ch>
> Cc: Florian Fainelli <f.fainelli@...il.com>; Andy Fleming
> <afleming@...escale.com>; netdev@...r.kernel.org; HEMANT RAMDASI
> <hramdasi@...co.com>; Julius Hemanth Pitti -X (jpitti - MONTA VISTA
> SOFTWARE INC at Cisco) <jpitti@...co.com>; harinikatakamlinux@...il.com
> Subject: Re: Marvell phy errata origins?
> 
> On 04/18/2017 07:41 AM, Harini Katakam wrote:
> > Hi Daniel,
> >
> >> -----Original Message-----
> >> From: Daniel Walker [mailto:danielwa@...co.com]
> >> Sent: Tuesday, April 18, 2017 8:05 PM
> >> To: Harini Katakam <harinik@...inx.com>; Andrew Lunn <andrew@...n.ch>
> >> Cc: Florian Fainelli <f.fainelli@...il.com>; Andy Fleming
> >> <afleming@...escale.com>; netdev@...r.kernel.org; HEMANT RAMDASI
> >> <hramdasi@...co.com>; Julius Hemanth Pitti -X (jpitti - MONTA VISTA
> >> SOFTWARE INC at Cisco) <jpitti@...co.com>
> >> Subject: Re: Marvell phy errata origins?
> >>
> >> On 04/18/2017 07:31 AM, Harini Katakam wrote:
> >>> Hi Daniel,
> >>>
> >>>> -----Original Message-----
> >>>> From: Daniel Walker [mailto:danielwa@...co.com]
> >>>> Sent: Tuesday, April 18, 2017 7:48 PM
> >>>> To: Andrew Lunn <andrew@...n.ch>
> >>>> Cc: Florian Fainelli <f.fainelli@...il.com>; Andy Fleming
> >>>> <afleming@...escale.com>; Harini Katakam <harinik@...inx.com>;
> >>>> netdev@...r.kernel.org; HEMANT RAMDASI <hramdasi@...co.com>;
> Julius
> >>>> Hemanth Pitti -X (jpitti - MONTA VISTA SOFTWARE INC at Cisco)
> >>>> <jpitti@...co.com>
> >>>> Subject: Re: Marvell phy errata origins?
> >>>>
> >>>> On 04/18/2017 07:04 AM, Andrew Lunn wrote:
> >>>>> On Tue, Apr 18, 2017 at 06:16:33AM -0700, Daniel Walker wrote:
> >>> <snip>
> >>>>>> In Harini's commit
> >>>>>> message for ,
> >>>>>>
> >>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gi
> >>>>>> t/ co mmit/drivers/net/phy/marvell.c?id=3ec0a0f10ceb
> >>>>>>
> >>>>>> "This function has a sequence accessing Page 5 and Register 31,
> >>>>>> both of which are not defined or reserved for this PHY"
> >>>>>>
> >>>>>> For the 88E1112 we see that these are "Factory Test Modes" which
> >>>>>> the contents of are not documented. They aren't really "not
> >>>>>> defied", and aren't really "reserved" .. Marvell support claims
> >>>>>> they don't support these drivers, and Freescale seems to be
> >>>>>> adding these drivers, and the line we are looking at.
> >>>>>>
> >>>>>> We had some issues with our PHY which were corrected with the
> >>>>>> same patch Harini used but modified for the M88E1112. We're
> >>>>>> trying to get to the bottom of where this code came from and what
> >>>>>> it was suppose to be doing.
> >>>>> I tried to find this errata fix in the Marvell reference code. And
> >>>>> failed to find it. But it is "Vendor Crap" code, hard to find
> >>>>> anything in it.
> >>>>>
> >>>>> My guess is, this errata just applies to one model of PHY, maybe
> >>>>> even one revision of one model of a PHY. The hard bit is figuring
> >>>>> out what actually needs it. Do you have access to Marvell datasheets?
> >>> I have access to the datasheets for 88E1111, 88E1112 and 88E1116
> >>> (and another family 151x) - None of them have these register details
> >>> or the errata
> >> documented.
> >>
> >> http://www.dexsilicium.com/Marvell_88E1112.pd
> >>
> >>
> >> Is this the same datasheet ? In this one on page 81 there is page 5
> >> register 31 is "Factory Test Modes" , do you not have that?
> > Yes, it is the same datasheet. That is what I meant - it just says
> > factory test modes But there is no register description.
> 
> I would call that undocumented. I suspect there are things inside the "Factory
> Test Modes" which could be helpful to fix errata. Things which Marvell might not
> want to document universally.

OK, agreed.

> 
> Can you describe what sort of issue you found which was the motivation for
> your patch ? Or did you remove the code because you did not know what it was
> used for?
> 

I added this patch for 88E1111 because that datasheet does not even have
Page 5 Reg 31 as "Factory Test mode" - it is reserved space.
Any access to that register failed. Since this register was clearly not part of
88E1111 PHY and irrelevant, I removed that code.

Regards,
Harini