Re: [devicetree-org/dt-schema] schemas: introduce assigned-clock-sscs (PR #154)

[Peng Fan <peng.fan@oss.nxp.com>]

On Thu, Feb 13, 2025 at 02:29:41PM +0100, Geert Uytterhoeven wrote:
>Hi Peng,
>
>On Thu, 13 Feb 2025 at 13:35, Peng Fan <peng.fan@oss.nxp.com> wrote:
>> On Thu, Feb 13, 2025 at 11:16:31AM +0100, Geert Uytterhoeven wrote:
>> >On Fri, 24 Jan 2025 at 15:42, Krzysztof Kozlowski <krzk@kernel.org> wrote:
>> >> Just FYI, below is a foward of pull request for dtschema for bindings
>> >> adding spread spectrum to clocks. As Clock framework maintainers this
>> >> might be relevant to you.
>> >>
>> >> -------- Forwarded Message --------
>> >> Subject: [devicetree-org/dt-schema] schemas: introduce
>> >> assigned-clock-sscs (PR #154)
>> >> Date: Fri, 24 Jan 2025 04:31:30 -0800
>> >> From: Peng Fan <notifications@github.com>
>> >> Reply-To: devicetree-org/dt-schema
>> >> <reply+ACPRLI5YLXX27TFZX2P7NVOFT5USFEVBNHHKO4ZXHM@reply.github.com>
>> >> To: devicetree-org/dt-schema <dt-schema@noreply.github.com>
>> >> CC: Subscribed <subscribed@noreply.github.com>
>> >>
>> >> To support spread spectrum clock, introduce assigned-clock-sscs, it is
>> >> an uint32-matrix with format multiple elements of below
>> >> &lt;modfreq spreadpercentage modmethod&gt;, &lt;...&gt;
>> >> You can view, comment on, or merge this pull request online at:
>> >>
>> >>   https://github.com/devicetree-org/dt-schema/pull/154
>> >>
>> >> -- Commit Summary --
>> >>
>> >>   * schemas: introduce assigned-clock-sscs
>> >
>> >>   assigned-clock-sscs:
>> >>     $ref: /schemas/types.yaml#/definitions/uint32-matrix
>> >>     items:
>> >>       items:
>> >>         - description: The modulation frequency
>> >>         - description: The modulation depth in permyriad
>> >>         - description: The modulation method, down(2), up(1), center(0)
>> >
>> >Is there a way to explicitly disable it, if it was enabled by the
>> >firmware? See also my comment in "Re: [PATCH v2 1/4] clk: Introduce
>>
>> The binding here is just to describe the parameter to configure
>> spread spectrum of a clk.
>>
>> To disable spread spectrum, the clk_hw_set_spread_spectrum could be
>> used with enable as false or as you suggested using CLK_SSC_NONE_SPREAD?
>
>But the bindings don't have an enable flag...

The modulation method maybe updated to
down(3), up(2), center(1), no modulation(0).

Then no need a separate entry for enable.

Thanks,
Peng.

>
>> >clk_hw_set_spread_spectrum".
>> >
>> >>           minimum: 0
>> >>           maximum: 2
>> >
>> >What's the meaning of these limits?
>>
>> Modulation has three methods:
>> Down-spread modulation
>> Up-spread modulation
>> Center-spread modulation.
>>
>> I use 2 for down, 1 for up, 0 for center here. So the limits:
>> min: 0, max: 2.
>
>Silly me, they apply to the last description...
>
>Gr{oetje,eeting}s,
>
>                        Geert
>
>-- 
>Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
>In personal conversations with technical people, I call myself a hacker. But
>when I'm talking to journalists I just say "programmer" or something like that.
>                                -- Linus Torvalds
>