netdev - Re: [PATCH RFC net-next 0/3] net: phy: sfp: Warn when using generic PHY driver

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Message-ID: <cf5eb510-6130-c417-a618-74c34dafa72e@gmail.com>
Date:   Tue, 6 Nov 2018 16:09:35 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, andrew@...n.ch
Subject: Re: [PATCH RFC net-next 0/3] net: phy: sfp: Warn when using generic
 PHY driver

On 11/6/18 4:03 PM, Russell King - ARM Linux wrote:
> On Tue, Nov 06, 2018 at 03:38:44PM -0800, David Miller wrote:
>> From: Florian Fainelli <f.fainelli@...il.com>
>> Date: Tue,  6 Nov 2018 15:29:10 -0800
>>
>>> This patch series allows warning an user that the generic PHY driver(s)
>>> are used when a SFP incorporates a PHY (e.g: 1000BaseT SFP) which is
>>> likely not going to work at all.
>>>
>>> Let me know if you would want to do that differently.
>>
>> Is there ever a possibility that the generic PHY driver could work
>> in an SFP situation?
> 
> I don't yet see the reason for Florian's patch series - all the Marvell
> 88e1111 based modules I have, or have come across in information from
> manufacturers self-configure themselves and don't really need the
> Marvell 1G PHY driver.
> 
> For example, the Source Photonics were offering a range of 1GbaseT
> modules with the 88e1111 programmed in different modes, but published
> instructions for the register accesses to configure them differently
> (eg, SGMII vs 1000base-X interface facing the MAC).  Depending on
> the module part number determines which mode the PHY has been
> programmed to come up in.
> 
> So in theory, you don't need any PHY driver for these modules - but
> it's useful to have a functional PHY driver to be able to read out
> the negotiated flow control results.
> 
> I'd like more information from Florian about the reasoning behind
> this patch series before it's merged.
> 

The module that I am using [1] would not work, as in , no link up being
reported without turning on the Marvell PHY driver:

https://www.amazon.com/dp/B01LW2P72V/ref=twister_B07F3WQJQX?_encoding=UTF8&psc=1

this module uses a 88E1111 PHY as well (OUI: 0x01410cc2).
-- 
Florian