On Tue, 2015-05-05 at 16:02 -0500, Liberman Igal-B31950 wrote:
>
>
> Regards,
> Igal Liberman.
>
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Saturday, May 02, 2015 2:43 AM
> > To: Liberman Igal-B31950
> > Cc: devicet...@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; Tang
> > Yuantian-B29983
> > Subject: Re: [v3] dt/bindings: qoriq-clock: Add binding for FMan clock mux
> >
> > On Thu, 2015-04-30 at 09:28 -0500, Liberman Igal-B31950 wrote:
> > > > -----Original Message-----
> > > > From: Wood Scott-B07421
> > > > Sent: Thursday, April 30, 2015 3:31 AM
> > > > To: Liberman Igal-B31950
> > > > Cc: devicet...@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; Tang
> > > > Yuantian-B29983
> > > > Subject: Re: [v3] dt/bindings: qoriq-clock: Add binding for FMan
> > > > clock mux
> > > >
> > > > On Wed, 2015-04-22 at 05:47 -0500, Liberman Igal-B31950 wrote:
> > > > > We have 2 cases:
> > > > > - Devices (T2/T4/B4) with CLKCG1HWACSR register.
> > > > > - Devices (Pxxxx, T1) without CLKCG1HWACSR register (Pxxxx
> > > > devices
> > > > > have many options, T1 has only one option)
> > > > >
> > > > > For the first group, we can have " qoriq-hwacsr" property in the clock
> > node.
> > > >
> > > > No, we're not going to describe every register with its own property.
> > > > Describe the chip and let the driver be the place with the knowledge
> > > > of what each chip is like.
> > > >
> > >
> > > I think that FMan clock mux (as we defined it) is similar to other muxes
> > available in our SoC.
> >
> > I realize that. I'm saying the way we described existing muxes seems to be
> > a
> > mistake. We're putting too much complexity in the device tree.
> > Better to put the complexity in a place that isn't stable ABI.
> >
> > > If we take T4 as example, it has 3 muxes defined in the device tree (mux0,
> > mux1 and mux2).
> > > Each mux has its own reg property (and clock providers).
> > > mux2: mux2@40 {
> > > #clock-cells = <0>;
> > > reg = <0x40 0x4>;
> > > compatible = "fsl,qoriq-core-mux-2.0";
> > > clocks = <&pll3 0>, <&pll3 1>, <&pll3 2>,
> > > <&pll4 0>, <&pll4 1>, <&pll4 2>;
> > > clock-names = "pll3", "pll3-div2", "pll3-div4",
> > > "pll4", "pll4-div2", "pll4-div4";
> > > clock-output-names = "cmux2";
> > > };
> > >
> > > I agree that "fm1-clk-mux" need to be moved from the "guts" node to
> > "clockgen" node.
> >
> > That's not what I was saying. I'm saying get rid of the node entirely, in
> > favor
> > of having the clockgen node itself be a clock source with multiple post-mux
> > outputs.
> >
>
> Scott,
> Currently the clockgen node has a number of sub nodes (platform clock,
> sysclock, PLLs and muxes, the number of muxes/PLLs is SoC dependent).
> The clockgen node has reg property, however, all other nodes have reg
> property too (The clockgen points to the clocking block address and the sub
> nodes point to the specific register in the clock block).
> Do you want to change this structure completely?
Yes, I want to change it completely (while ensuring the kernel still
works, albeit without new functionality, with older device trees).
> I'm not sure I understand the exact way you want see those nodes (in the
> final state).
Something like:
clockgen: global-utilities@e1000 {
compatible = "fsl,<whatever>-clockgen";
clock-frequency = <...>;
reg = <0xe1000 0x1000>;
#clock-cells = <2>;
};
cpu0: PowerPC,e6500@0 {
device_type = "cpu";
reg = <0 1>;
clocks = <&clockgen 0 0>;
next-level-cache = <&L2_1>;
fsl,portid-mapping = <0x80000000>;
};
cpu4: PowerPC,e6500@0 {
device_type = "cpu";
reg = <4 5>;
clocks = <&clockgen 0 1>;
next-level-cache = <&L2_1>;
fsl,portid-mapping = <0x80000000>;
};
fman@... {
...
clocks = <&clockgen 1 0>;
...
};
...with the clockgen binding explaining the format of the clock
specifier, and the clockgen driver containing the chip-specific muxing
details.
-Scott
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