Re: [RFC] phy: micrel: Convert micrel PHY driver to use OF

[Dinh Nguyen <dinguyen@altera.com>]

On Thu, 2013-08-22 at 08:34 +0200, Sascha Hauer wrote:
> On Wed, Aug 21, 2013 at 10:13:47PM -0700, Olof Johansson wrote:
> > (adding devicetree@vger.kernel.org)
> > 
> > 
> > On Tue, Aug 13, 2013 at 11:42:36AM -0500, dinguyen@altera.com wrote:
> > > ---
> > > Hello,
> > > 
> > > I would like to solicit comments on the need to convert the ethernet PHY
> > > drivers to use OF/device trees? For the platform that I'm interested in,
> > > SOCFPGA, it is using the stmicro ethernet driver. It has a Micrel PHY
> > > on the board. The only way that I know of how to change the skew settings
> > > for the phy is through a board level initialization.
> > > 
> > > One of the ARM maintainers suggested that perhaps refactoring the ethernet
> > > driver to use device tree would be nice. But that would not help me with
> > > configuring the PHY settings.
> > > 
> > > So a little investigation led me to believe that refactoring the /net/phy
> > > drivers into a device tree implementation would help greatly. I was thinking
> > > it could be done like the pinctrl or some of the usb/phy driver.
> > > 
> > > Since I am only familiar with the ARM SoC space, I want to make sure that
> > > this idea is right approach. I can start with the micrel PHY driver
> > > first, as that is the only HW I have access to.
> > 
> > Hi,
> > 
> > Sorry for the slow reply here.
> > 
> > I don't think this is quite the right approach.
> > 
> > What you want to do is to make the phy devices register based on device tree
> > contents, which also means removing the run function, or rather moving it to
> > a generic run function in the phy subsystem that acts based on device tree
> > contents instead of a hard-coded per-board run function.
> > 
> > It sounds like defining that binding might end up getting complicated.
> > I suggest you consider recruiting some of the more seasoned devicetree folks on
> > this endeavor.
> > 
> > It's possible that you'll mostly have per-vendor/phy type properties to tune
> > the various settings, but it's also likely that you will have some generic and
> > shared (optional) properties such as gpios for resetting, or regulators for
> > powering, the phy.
> 
> This patch recently was merged:
> 
> http://patchwork.ozlabs.org/patch/268661/
> 
> It solves exactly the same problem of specifying the skew settings.

Thanks for the information. This is great stuff!

Dinh
> 
> Sascha
>