linux-kernel - RE: [PATCH v4 0/5] clk: Support spread spectrum and use it in clk-scmi

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Message-ID:
 <PAXPR04MB8459265997E9822F17AD2BC0881CA@PAXPR04MB8459.eurprd04.prod.outlook.com>
Date: Wed, 24 Sep 2025 14:44:21 +0000
From: Peng Fan <peng.fan@....com>
To: Michael Turquette <mturquette@...libre.com>, Stephen Boyd
	<sboyd@...nel.org>, Sudeep Holla <sudeep.holla@....com>, Cristian Marussi
	<cristian.marussi@....com>, Marco Felsch <m.felsch@...gutronix.de>, Rob
 Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor
 Dooley <conor+dt@...nel.org>, Brian Masney <bmasney@...hat.com>
CC: Dan Carpenter <dan.carpenter@...aro.org>, Geert Uytterhoeven
	<geert@...ux-m68k.org>, "linux-clk@...r.kernel.org"
	<linux-clk@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "arm-scmi@...r.kernel.org"
	<arm-scmi@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>
Subject: RE: [PATCH v4 0/5] clk: Support spread spectrum and use it in
 clk-scmi

Hi Stephen,

> Subject: [PATCH v4 0/5] clk: Support spread spectrum and use it in clk-
> scmi

Since clk-scmi.c for spread spectrum support needs some big changes,
we may need to change scmi framework to make OEM extension
in an elegant way. This will needs some time.

To patch 1-4, do you think is it ok to be in linux tree without patch 5?
If yes, I will post V5 soon with your comments in patch 2 addressed.
Otherwise I have to carry patch 1-4 in future clk-scmi patches.

Thanks,
Peng.

> 
> Since the assigned-clock-sscs property [1] has been accepted into the
> device tree schema, we can now support it in the Linux clock driver.
> Therefore, I’ve picked up the previously submitted work [2] titled “clk:
> Support spread spectrum and use it in clk-pll144x and clk-scmi.”
> As more than six months have passed since [2] was posted, I’m treating
> this patchset as a new submission rather than a v3.
> 
> - Introduce clk_set_spread_spectrum to set the parameters for enabling
>   spread spectrum of a clock.
> - Parse 'assigned-clock-sscs' and configure it by default before using the
>   clock. This property is parsed before parsing clock rate.
> - Enable this feature for clk-scmi on i.MX95.
> 
> Because SCMI spec will not include spread spectrum as a standard
> extension, we still need to use NXP i.MX OEM extension.
> 
> [1] https://github.com/devicetree-org/dt-schema/pull/154
> [2] https://lore.kernel.org/all/20250205-clk-ssc-v2-0-
> fa73083caa92@....com/
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
> Changes in v4:
> - Add R-b for patch 1 from Brian
> - Drop unecessary change in patch 4 Per Brian
> - Link to v3: https://lore.kernel.org/r/20250912-clk-ssc-version1-v3-0-
> fd1e07476ba1@....com
> 
> Changes in v3:
> - New patch 1 for dt-bindings per comment from Brian
>   https://lore.kernel.org/all/aLeEFzXkPog_dt2B@x1/
>   This might not be good to add a new dt-binding file in v3. But this is
>   quite a simple file that just has four macros to encode modulation
>   method. So hope this is fine for DT maintainers.
> - Add Brain's R-b for patch 2
> - New patch 3 to add Kunit test per Brain. Since Brain helped
>   draft part of the code, I added Co-developed-by tag from Brain.
> - Link to v2: https://lore.kernel.org/r/20250901-clk-ssc-version1-v2-0-
> 1d0a486dffe6@....com
> 
> Changes in v2:
> - Simplify the code in patch 2 per Dan Carpenter and Brian Masney
> - Rebased to next-20250829
> - Link to v1: https://lore.kernel.org/r/20250812-clk-ssc-version1-v1-0-
> cef60f20d770@....com
> 
> ---
> Peng Fan (5):
>       dt-bindings: clock: Add spread spectrum definition
>       clk: Introduce clk_hw_set_spread_spectrum
>       clk: conf: Support assigned-clock-sscs
>       clk: Add KUnit tests for assigned-clock-sscs
>       clk: scmi: Support Spread Spectrum for NXP i.MX95
> 
>  drivers/clk/Makefile                               |   6 +
>  drivers/clk/clk-conf.c                             |  69 ++++++++++++
>  drivers/clk/clk-scmi.c                             |  64 ++++++++++-
>  drivers/clk/clk.c                                  |  26 +++++
>  drivers/clk/clk_test.c                             | 121 ++++++++++++++++++++-
>  drivers/clk/kunit_clk_assigned_rates.h             |  10 ++
>  drivers/clk/kunit_clk_assigned_rates_multiple.dtso |   6 +
>  ...kunit_clk_assigned_rates_multiple_consumer.dtso |   6 +
>  drivers/clk/kunit_clk_assigned_rates_one.dtso      |   3 +
>  .../clk/kunit_clk_assigned_rates_one_consumer.dtso |   3 +
>  .../clk/kunit_clk_assigned_rates_u64_multiple.dtso |   6 +
>  ...t_clk_assigned_rates_u64_multiple_consumer.dtso |   6 +
>  drivers/clk/kunit_clk_assigned_rates_u64_one.dtso  |   3 +
>  .../kunit_clk_assigned_rates_u64_one_consumer.dtso |   3 +
>  drivers/clk/kunit_clk_assigned_sscs_null.dtso      |  16 +++
>  .../clk/kunit_clk_assigned_sscs_null_consumer.dtso |  20 ++++
>  drivers/clk/kunit_clk_assigned_sscs_without.dtso   |  15 +++
>  .../kunit_clk_assigned_sscs_without_consumer.dtso  |  19 ++++
>  drivers/clk/kunit_clk_assigned_sscs_zero.dtso      |  12 ++
>  .../clk/kunit_clk_assigned_sscs_zero_consumer.dtso |  16 +++
>  include/dt-bindings/clock/clock.h                  |  14 +++
>  include/linux/clk-provider.h                       |  22 ++++
>  include/linux/scmi_protocol.h                      |   5 +
>  23 files changed, 464 insertions(+), 7 deletions(-)
> ---
> base-commit: 8941e75c0f122fdd76dc54ed45c4ce917587e006
> change-id: 20250812-clk-ssc-version1-acf6f6efbd96
> 
> Best regards,
> --
> Peng Fan <peng.fan@....com>