linux-kernel - RE: [PATCH v4 3/5] clk: conf: Support assigned-clock-sscs

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Message-ID:
 <PAXPR04MB845901FCD95CFEBCF22AB34588E1A@PAXPR04MB8459.eurprd04.prod.outlook.com>
Date: Wed, 8 Oct 2025 12:31:14 +0000
From: Peng Fan <peng.fan@....com>
To: Sebin Francis <sebin.francis@...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>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Brian
 Masney <bmasney@...hat.com>, Dhruva Gole <d-gole@...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 3/5] clk: conf: Support assigned-clock-sscs

> Subject: Re: [PATCH v4 3/5] clk: conf: Support assigned-clock-sscs
...
> >    * of_clk_set_defaults() - parse and set assigned clocks configuration
> >    * @node: device node to apply clock settings for @@ -174,6
> +239,10
> > @@ int of_clk_set_defaults(struct device_node *node, bool
> clk_supplier)
> >   	if (!node)
> >   		return 0;
> >
> > +	rc = __set_clk_spread_spectrum(node, clk_supplier);
> > +	if (rc < 0)
> > +		return rc;
> > +
> >   	rc = __set_clk_parents(node, clk_supplier);
> >   	if (rc < 0)
> >   		return rc;
> >
> 
> Here you are setting the clock's ssc before the setting the parent and
> rate, is it possible to move it below setting of parent and rate?
> because the ssc is enabled after the parent and rate is set to a clock.

The idea is setting ssc is to let driver/firmware latch the configuration,
and when set rate, the driver/firmware will configure the rate
with ssc settings. And this is what i.MX SCMI firmware implements.

Per my understanding, from hardware perspective, when setting rate,
ssc should be set together if need to enable ssc.

So TI's future platform may take NXP firmware's approach.

Thanks,
Peng. 

> 
> Thanks
> Sebin