Subject: [PATCHv9 30/43] ARM: dts: am33xx clock data

From: [email-masked] (Tero Kristo)
Date: Sat, 26 Oct 2013 15:46:26 +0300

On 10/26/2013 03:36 AM, Jan L?bbe wrote:
> On Fri, 2013-10-25 at 18:57 +0300, Tero Kristo wrote:
>> +       mcasp0_fck: mcasp0_fck {
>> +               #clock-cells = <0>;
>> +               compatible = "fixed-factor-clock";
>> +               clocks = <&sys_clkin_ck>;
>> +               clock-mult = <1>;
>> +               clock-div = <1>;
>> +       };
>> +
>> +       mcasp1_fck: mcasp1_fck {
>> +               #clock-cells = <0>;
>> +               compatible = "fixed-factor-clock";
>> +               clocks = <&sys_clkin_ck>;
>> +               clock-mult = <1>;
>> +               clock-div = <1>;
>> +       };
>
> What is you use case for these clocks with a fixed factor of 1? Wouldn't
> it be simpler to just use sys_clkin_ck from the devices?

This is just kind of a dummy clock node for the driver use, so that it 
is simpler for them to find their clocks. If these are dropped, the 
drivers need to know that instead of their old own mcaspX_fck, they now 
need to directly connect to sys_clkin_ck. This also allows to track 
usecounts for the clocks better, if you don't have the mcaspX_fck:s for 
example, you will just have a usecount of 25 for the sys_clkin_ck, but 
don't really know who is using it. Also, other SoCs most likely have the 
same name in use, so just to keep the clock data compatible across SoCs.

These files are also completely autogenerated from the existing clock 
data under mach-omap2, and these nodes exist there.

But yea, no hard requirement.

-Tero