Re: [PATCH 4/6] dt-bindings: clock: st,stm32-rcc: support spread spectrum clocking
From: Rob Herring <robh@kernel.org>
Date: 2025-01-08 23:48:08
Also in:
linux-clk, linux-devicetree, lkml
On Sun, Jan 05, 2025 at 07:14:16PM +0100, Dario Binacchi wrote:
quoted hunk ↗ jump to hunk
The addition of DT bindings for enabling and tuning spread spectrum clocking generation is available only for the main PLL. Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com> --- .../bindings/clock/st,stm32-rcc.yaml | 27 +++++++++++++++++++ 1 file changed, 27 insertions(+)diff --git a/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml b/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml index ae9e5b26d876..c345d3ff3fc4 100644 --- a/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml +++ b/Documentation/devicetree/bindings/clock/st,stm32-rcc.yaml@@ -77,6 +77,26 @@ properties: Phandle to system configuration controller. It can be used to control the power domain circuitry. + st,ssc-modfreq-hz: + description: + The modulation frequency for main PLL (in Hz)
No constraints?
+ + st,ssc-moddepth-permyriad: + $ref: /schemas/types.yaml#/definitions/uint32 + description: + The modulation rate for main PLL (in permyriad, i.e. 0.01%) + minimum: 25 + maximum: 200 + + st,ssc-modmethod: + $ref: /schemas/types.yaml#/definitions/non-unique-string-array + description: + The modulation techniques for main PLL. + items: + enum: + - center-spread + - down-spread
What's the default? If there's only 2 possibilities, then you can use a boolean instead. Though I assume you want to support spread-spectrum disabled. Are there dependencies between these properties?
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+ required: - compatible - reg@@ -97,6 +117,10 @@ allOf: const: 1 description: | The clock index for the specified type. + st,ssc-modfreq-hz: false + st,ssc-moddepth-permyriad: false + st,ssc-modmethod: false + else: properties: '#clock-cells':@@ -118,6 +142,9 @@ examples: reg = <0x40023800 0x400>; clocks = <&clk_hse>, <&clk_i2s_ckin>; st,syscfg = <&pwrcfg>; + st,ssc-modfreq-hz = <10000>; + st,ssc-moddepth-permyriad = <200>; + st,ssc-modmethod = "center-spread"; }; - |-- 2.43.0