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

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

[Geert Uytterhoeven]

CC devicetree

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
clk_hw_set_spread_spectrum".

>           minimum: 0
>           maximum: 2

What's the meaning of these limits?

[1] https://lore.kernel.or/CAMuHMdWn+sKiC1B4MF1vHwS2ArFYQXGzpYi2EcsyERPSCc9bvQ@mail.gmail.com

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

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

[Geert Uytterhoeven]

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...

> >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

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

[Peng Fan]

Hi Geert,

On Thu, Feb 13, 2025 at 11:16:31AM +0100, Geert Uytterhoeven wrote:
>CC devicetree
>
>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?

>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.

Thanks,
Peng

>
>[1] https://lore.kernel.org/CAMuHMdWn+sKiC1B4MF1vHwS2ArFYQXGzpYi2EcsyERPSCc9bvQ@mail.gmail.com
>
>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
>

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

[Peng Fan]

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
>