[PATCH 7/7] commands: Add mdio_read and mdio_write

[Trent Piepho]

On Tue, 2016-01-26 at 18:09 -0800, Andrey Smirnov wrote:
> On Tue, Jan 26, 2016 at 1:55 PM, Sascha Hauer <s.hauer at pengutronix.de> wrote:
> > On Mon, Jan 25, 2016 at 09:55:58PM -0800, Andrey Smirnov wrote:
> >> Add commands for low-level access to MDIO bus.
> >
> > Do we really need this? We can already read/write phy registers using
> > /dev/phyx which imo is quite convenient since it can be accessed with
> > regular md/mw commands.
> >

> Just to explain the purpose of this patch -- there are number of
> reasons we might want to be able to access "unregistered" PHYs:
> 
> - Not all MDIO attached devices would have PHYSID1,2 registers
> available which might cause mdiobus_scan() to not detect those PHYs
> 
> - MDIO bus troubleshooting

Maybe instead have a command that adds a phydev to a mdio bus?  So if
you wanted to issue commands to some address that doesn't have a phy
detected you could add a dummy phy using this command and then use
standard md/mw and so on commands with it.  There is still a new command
but it does not have to duplicate existing functionality this way.