Re: [PATCH 1/2 v3] powerpc/fsl: Use new clockgen binding

[Scott Wood]

On Wed, 2018-12-12 at 01:57 +0000, Andy Tang wrote:
> > -----Original Message-----
> > From: Scott Wood <oss@xxxxxxxxxxxx>
> > Sent: 2018å11æ26æ 9:19
> > To: Andy Tang <andy.tang@xxxxxxx>
> > Cc: mturquette@xxxxxxxxxxxx; sboyd@xxxxxxxxxx; robh+dt@xxxxxxxxxx;
> > mark.rutland@xxxxxxx; benh@xxxxxxxxxxxxxxxxxxx; paulus@xxxxxxxxx;
> > mpe@xxxxxxxxxxxxxx; linux-clk@xxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > linuxppc-dev@xxxxxxxxxxxxxxxx
> > Subject: Re: [PATCH 1/2 v3] powerpc/fsl: Use new clockgen binding
> > 
> > On Wed, 2018-10-31 at 14:57 +0800, Yuantian Tang wrote:
> > > From: Scott Wood <oss@xxxxxxxxxxxx>
> > > 
> > > The driver retains compatibility with old device trees, but we don't
> > > want the old nodes lying around to be copied, or used as a reference
> > > (some of the mux options are incorrect), or even just being clutter.
> > > 
> > > 
> > > +sysclk: sysclk {
> > > +	compatible = "fixed-clock";
> > > +	#clock-cells = <0>;
> > > +	clock-frequency = <100000000>;
> > > +	clock-output-names = "sysclk";
> > > +};
> > > +
> > >  clockgen: global-utilities@e1000 {
> > 
> > The U-Boot fixup won't work with this.  U-Boot patches the frequency
> > directly into the clockgen node (BTW, this is another reason to preserve
> > the generic
> > 1.0/2.0 compatible string).  The new binding does not require an input
> > clock node when it is provided as clock-frequency directly in the clockgen
> > node -- and the sysclk node was not in my original patch (nor did you note
> > that you made changes from that original).  Why did you add it?
> > 
> > I would just remove it when applying, but I'm concerned that this
> > indicates
> > a lack of testing (and I don't have the hardware access to test it myself,
> > except on t4240) -- unless the 100 MHz sysclk just happened to be correct
> > on the machines you tested (which would also be a test coverage
> > problem)?
> 
> [Andy] You are right. Sysclk may not be useful anymore. 
> Uboot will fixup the clockgen node correctly. Please apply this patch
> without sysclk. We will
> test it and catch the error if the clock is not fixed correctly.

OK.

> BTW, which git tree are you going to apply it on? This one?
> 
https://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux.git/log/?h=next

That will be the branch I use to send the patches to Michael, but it's not a
branch that is kept constantly updated.  If you're asking what tree to base
future patches on, that would generally be the next branch of
powerpc/linux.git (unless you depend on something else that isn't there yet).

-Scott