linux-kernel - Re: [PATCH v2 2/3] clk: conf: Support assigned-clock-sscs

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Message-ID: <20250907131209.GB26925@nxa18884-linux.ap.freescale.net>
Date: Sun, 7 Sep 2025 21:12:09 +0800
From: Peng Fan <peng.fan@....nxp.com>
To: Brian Masney <bmasney@...hat.com>
Cc: Peng Fan <peng.fan@....com>,
	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>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
	arm-scmi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/3] clk: conf: Support assigned-clock-sscs

Hi Brian,

On Tue, Sep 02, 2025 at 07:56:07PM -0400, Brian Masney wrote:
>Hi Peng,
>
>On Mon, Sep 01, 2025 at 11:51:46AM +0800, Peng Fan wrote:
>> Parse the Spread Spectrum Configuration(SSC) from device tree and configure
>> them before using the clock.
>> 
>> Each SSC is three u32 elements which means '<modfreq spreaddepth
>> modmethod>', so assigned-clock-sscs is an array of multiple three u32
>> elements.
>> 
>> Signed-off-by: Peng Fan <peng.fan@....com>
>
>Stephen has also been asking for kunit tests to be added for new
>functionality in the clk core. There's already one kunit test that
>calls of_clk_set_defaults(). I attached a very rough draft of a patch
>showing that it'd be possible to mock this up in a test with what's
>already there. I set a log statement with the configuration from
>device tree:

Appreciate your help on this. I was not aware of kunit tests is required.
I will add one in V3.

>
>test_assigned_rate0: Spread Sprectrum Configuration: modfreq_hz=10000 spread_bp=3 method=1
>
>You can run the kunit tests with:
>
>./tools/testing/kunit/kunit.py run \
>	--kunitconfig drivers/clk/.kunitconfig \
>	--raw_output=all
>
>Additionally, what do you think about making a dt-bindings include file
>for CLK_SSC_CENTER_SPREAD + friends? Right now, the test illustrates
>that we need to hardcode the number from the clk-provider.h file inside
>the DTS.

ok to add a generic dt-bindings file for the the SSC Spread method.
I will add one in V3.

>
>Here's the patch and feel free to make it your own as you see fit.
>

Thanks a lot for sharing this.

Thanks,
Peng