RE: [PATCH 0/1] add MDIO bus multiplexer driven by a regmap device

-----Original Message-----
From: Andrew Lunn [mailto:andrew@lunn.ch]
Sent: Wednesday, 30 January, 2019 08:53 PM
To: Pankaj Bansal <redacted>
Cc: Florian Fainelli <f.fainelli@gmail.com>; netdev@vger.kernel.org; Varun Sethi
[off-list ref]
Subject: Re: [PATCH 0/1] add MDIO bus multiplexer driven by a regmap device

On Wed, Jan 30, 2019 at 11:21:57AM +0000, Pankaj Bansal wrote:

quoted

Add support for an MDIO bus multiplexer controlled by a regmap device,
like an FPGA.

These apis is an extension of the existing driver
drivers/net/phy/mdio-mux-mmioreg.c.

The problem with mmioreg driver is that it can operate only on memory
mapped devices.
but if we have a device that controls mdio muxing and that device is
controlled using i2c or spi, then it will not work.

Therefore, added apis that can be used by regmap device to control mdio mux.

Tested on a NXP LX2160AQDS board which uses the "QIXIS" FPGA attached
to the i2c bus.

This is my second attempt at this.
In my previous approach i wrote a separate driver for regmap apis. But
then i realized that it is not meant to control a specific device.
It is meant to control some registers of parent device. Therefore, IMO
this should not be a Platform driver and there should not be any
"compatible" property to which this driver is associated.

Hi Pankaj

It is not clear to me how you actually use this. You also need to document the
device tree binding. It could be when you write that documentation it then
becomes clear how it should be used.

This is not a new driver for a device. Which is why there is no compatible field that I have used in these APIs.
Should I create a new binding document for it ?

Do you have patches adding support for this to the LX2160AQDS?  Seeing that
would also help.

DTS representation: https://patchwork.ozlabs.org/patch/998278/
Usage Patch : https://patchwork.kernel.org/patch/10788345/

Thanks
	Andrew