netdev - Re: FWD: [PATCH v2] Marvell phy: add fiber status check for some components

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Date:	Mon, 11 Apr 2016 12:47:28 -0700
From:	Florian Fainelli <f.fainelli@...il.com>
To:	Andrew Lunn <andrew@...n.ch>
Cc:	netdev <netdev@...r.kernel.org>,
	charles-antoine.couret@...vision.fr
Subject: Re: FWD: [PATCH v2] Marvell phy: add fiber status check for some
 components

On 04/04/16 06:25, Andrew Lunn wrote:
>> >From 564b767163d19355a3b5efaad195e93796570c71 Mon Sep 17 00:00:00 2001
>> From: Charles-Antoine Couret <charles-antoine.couret@...vision.fr>
>> Date: Fri, 1 Apr 2016 16:16:35 +0200
>> Subject: [PATCH] Marvell phy: add fiber status check for some components
>>
>> Marvell's phy could have two modes: fiber and copper. Currently, the driver
>> checks only the copper mode registers to get the status link which could be
>> wrong.
>>
>> This commit add a handler to check fiber then copper status link.
>> If the fiber link is activated, the driver would use this information.
>> Else, it would use the copper status.
> 
> Hi Florian
> 
> What do you think about this?
> 
> This works for basic status information. But what about other ethtool
> options? Setting the speed and duplex, turning pause on/off, etc.

Agreed, it seems like a PHY configured for fiber will need to provide
these informations differently, or does the standard BMSR register
provide accurate information already?

> 
> Do we actually need to stay on page 1 if fibre is in use? How do we
> initially change to page 1 when the fibre link is still down?

I also do not feel very comfortable with reading the fiber status first,
and then copper and then combine these two. At the very best, could we
do something like:

- identify if the PHY is configured for fiber in drv->probe or
drv->config_init, retain that information
- have two paths in drv->read_status which take care of reading one
status or the other?

Are there other side effects for other register accesses (say,
statistics, or auto-negotiation) that need to be fiber vs. copper aware?

> 
> Should we be using the old mechanism to swap between TP, BNC and AUI
> to swap between copper and fibre?

Did you mean using ethtool -s <iface> port fibre for instance?
-- 
Florian