netdev - Re: Marvell phy errata origins?

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Message-ID: <1ab15dcd-196d-415a-c4ef-388a9b885b2f@cisco.com>
Date:   Tue, 18 Apr 2017 07:56:12 -0700
From:   Daniel Walker <danielwa@...co.com>
To:     Harini Katakam <harini.katakam@...inx.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?

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.git/
>>>>>> 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.

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?

Daniel