[PATCH] DT: add MDIO node for FMan node

[Shaohui Xie]

Best Regards, 
Shaohui Xie


> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Thursday, November 13, 2014 3:15 PM
> To: Xie Shaohui-B21989
> Cc: Liberman Igal-B31950; linuxppc-dev at lists.ozlabs.org;
> devicetree at vger.kernel.org; Medve Emilian-EMMEDVE1
> Subject: Re: [PATCH] DT: add MDIO node for FMan node
> 
> On Thu, 2014-11-13 at 01:11 -0600, Xie Shaohui-B21989 wrote:
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Thursday, November 13, 2014 2:17 PM
> > > To: Xie Shaohui-B21989
> > > Cc: Liberman Igal-B31950; linuxppc-dev at lists.ozlabs.org;
> > > devicetree at vger.kernel.org; Medve Emilian-EMMEDVE1
> > > Subject: Re: [PATCH] DT: add MDIO node for FMan node
> > >
> > > On Wed, 2014-11-12 at 07:40 -0600, Xie Shaohui-B21989 wrote:
> > > > > -----Original Message-----
> > > > > From: Wood Scott-B07421
> > > > > Sent: Wednesday, November 12, 2014 1:38 AM
> > > > > To: Xie Shaohui-B21989
> > > > > Cc: Liberman Igal-B31950; linuxppc-dev at lists.ozlabs.org;
> > > > > devicetree at vger.kernel.org; Medve Emilian-EMMEDVE1
> > > > > Subject: Re: [PATCH] DT: add MDIO node for FMan node
> > > > >
> > > > > On Tue, 2014-11-11 at 04:32 -0600, Xie Shaohui-B21989 wrote:
> > > > > > > -----Original Message-----
> > > > > > > From: Wood Scott-B07421
> > > > > > > Sent: Tuesday, November 11, 2014 8:23 AM
> > > > > > > To: shh.xie at gmail.com
> > > > > > > Cc: linuxppc-dev at lists.ozlabs.org;
> > > > > > > devicetree at vger.kernel.org; Medve Emilian-EMMEDVE1; Xie
> > > > > > > Shaohui-B21989
> > > > > > > Subject: Re: [PATCH] DT: add MDIO node for FMan node
> > > > > > >
> > > > > > > On Tue, 2014-11-04 at 19:56 +0800, shh.xie at gmail.com wrote:
> > > > > > > > From: Shaohui Xie <Shaohui.Xie at freescale.com>
> > > > > > > >
> > > > > > > > This binding is for FMan MDIO, it covers FMan v2 & FMan v3.
> > > > > > > >
> > > > > > > > Signed-off-by: Shaohui Xie <Shaohui.Xie at freescale.com>
> > > > > > > > ---
> > > > > > > > based on http://patchwork.ozlabs.org/patch/390351/
> > > > > > > > for 'next' of
> > > > > > > >
> git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux.
> > > > > > > > git
> > > > > > >
> > > > > > > Are there any other FMan pieces that are missing from the
> > > > > > > above
> > > patch?
> > > > > > [S.H] I'm adding Igal for this comment.
> > > > > >
> > > > > > >
> > > > > > > > +- bus-frequency
> > > > > > > > +		Usage: optional
> > > > > > > > +		Value type: <u32>
> > > > > > > > +		Definition: Default MDIO bus clock speed.
> > > > > > >
> > > > > > > Use clocks/clock-names
> > > > > > [S.H] The MDIO uses Fman clock and divides it to a proper
> > > > > > value which
> > > > > is specified by this property.
> > > > >
> > > > > Use clocks/clock-names to describe that relationship.
> > > > >
> > > >
> > > > [S.H] The MDIO node is sub-node and embedded in Fman node, the
> > > > clocks/clock-names is provided by Fman node, should repeat them in
> > > > MDIO node? For the default MDIO bus clock speed, maybe "clock-
> ranges"
> > > > should be used?
> > >
> > > It's a different clock.  You wouldn't be repeating.  If it's derived
> > > from the FMan clock, then maybe you don't need anything here (does
> > > the driver know what the divider is, or would that need to be
> > > specified in the device tree?), but no more clock-frequency/bus-
> frequency properties.
> > >
> > [S.H] The purpose here is to get a specific clock frequency, driver to
> use it to calculate the divider.
> > Then the Fman clock can be divided to the frequency.
> 
> Oh, so this is stating a desired frequency and not something that already
> exists?  What determines this frequency?  Is it based on board design, or
> just on the MDIO standard, etc?  I'm wondering if the device tree is the
> right place for it.
[S.H] Yes, a desired frequency which is different with MDIO standard.
The Fman clock and the divider determines this frequency.
Since Fman clock is different on different SoCs, so specify the desired frequency, 
then to get the proper divider.


Thanks.
shaohui