linux-kernel - Re: [PATCH v2 0/4] clk: Support spread spectrum and use it in clk-pll144x and clk-scmi

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Message-ID: <20250312160207.GA21518@nxa18884-linux>
Date: Thu, 13 Mar 2025 00:02:07 +0800
From: Peng Fan <peng.fan@....nxp.com>
To: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Russell King <linux@...linux.org.uk>,
	Sudeep Holla <sudeep.holla@....com>,
	Cristian Marussi <cristian.marussi@....com>,
	Abel Vesa <abelvesa@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk@...nel.org>
Cc: "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>,
	Dario Binacchi <dario.binacchi@...rulasolutions.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: Re: [PATCH v2 0/4] clk: Support spread spectrum and use it in
 clk-pll144x and clk-scmi

I am still waiting for a yes or no, or any suggestions.

Thanks,
Peng

On Mon, Feb 24, 2025 at 01:09:20PM +0000, Peng Fan (OSS) wrote:
>Hi Rob, Stephen,
>
>> Subject: [PATCH v2 0/4] clk: Support spread spectrum and use it in clk-
>> pll144x and clk-scmi
>
>Do you have time to give a look on patch 1,2 and the bindings
>part in https://github.com/devicetree-org/dt-schema/pull/154
>
>I would like to see if you agree on this approach or not, then
>I could work on next step to explore new method or else

>
>Thanks,
>Peng.
>
>> 
>> - 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. The pull request for this property is at [1]
>>   This property is parsed before parsing clock rate.
>> 
>> - Enable this feature for clk-scmi on i.MX95.
>>   This may not the best, since checking machine compatibles.
>>   I am thinking to provide an API scmi_get_vendor_info, then driver
>>   could use it for OEM stuff, such as
>>   if (scmi_get_vendor_info returns NXP_IMX)
>>       ops->set_spread_spectrum = scmi_clk_set_spread_spectrum;
>> 
>> [1] https://github.com/devicetree-org/dt-schema/pull/154
>> 
>> Signed-off-by: Peng Fan <peng.fan@....com>
>> ---
>> Changes in v2:
>> - Rename to clk_hw_set_spread_spectrum and not export it as
>> consumer API.
>> - Fix error handling
>> - The enable parameter is still kept, because 0% is valid per
>>   https://www.ti.com/lit/an/scaa103/scaa103.pdf?ts=1738667308903
>>   https://www.synopsys.com/blogs/chip-design/understanding-pcie-
>> spread-spectrum-clocking.html
>> - Include the i.MX clk pll14xx which was an effort to enable SSC on
>> i.MX8MN from https://lore.kernel.org/all/20250118124044.157308-1-
>> dario.binacchi@...rulasolutions.com/
>>   With this patchset, things could be simplied a lot.
>> - Update the clk-scmi extconfig, marked as not apply, because spec not
>> settle down.
>> - Link to v1: https://lore.kernel.org/linux-clk/20250124-clk-ssc-v1-0-
>> 2d39f6baf2af@....com/T/#mce926ef10d3d9c1c960c21867c2f1509f1
>> f87cb9
>> 
>> ---
>> Peng Fan (4):
>>       clk: Introduce clk_hw_set_spread_spectrum
>>       clk: conf: Support assigned-clock-sscs
>>       clk: imx: pll14xx: support spread spectrum clock generation
>>       [NOT APPLY] clk: scmi: Support spread spectrum
>> 
>>  drivers/clk/clk-conf.c        | 70
>> +++++++++++++++++++++++++++++++++++++++++++
>>  drivers/clk/clk-scmi.c        | 47 +++++++++++++++++++++++++++--
>>  drivers/clk/clk.c             | 34 +++++++++++++++++++++
>>  drivers/clk/imx/clk-pll14xx.c | 66
>> ++++++++++++++++++++++++++++++++++++++++
>>  include/linux/clk-provider.h  | 32 ++++++++++++++++++++
>>  include/linux/clk.h           | 22 ++++++++++++++
>>  include/linux/scmi_protocol.h |  6 ++++
>>  7 files changed, 275 insertions(+), 2 deletions(-)
>> ---
>> base-commit: 40b8e93e17bff4a4e0cc129e04f9fdf5daa5397e
>> change-id: 20250124-clk-ssc-f3d70fb6cd1c
>> 
>> Best regards,
>> --
>> Peng Fan <peng.fan@....com>
>