| Message ID | 20250105181525.1370822-5-dario.binacchi@amarulasolutions.com |
|---|---|
| State | New |
| Headers | show |
| Series |
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| Related | show |
On Sun, Jan 05, 2025 at 07:14:16PM +0100, Dario Binacchi wrote: > 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? > + > 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 > To unsubscribe from this group and stop receiving emails from it, send an email to linux-amarula+unsubscribe@amarulasolutions.com.
Hello Rob, On Thu, Jan 9, 2025 at 12:48 AM Rob Herring <robh@kernel.org> wrote: > > On Sun, Jan 05, 2025 at 07:14:16PM +0100, Dario Binacchi wrote: > > 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? They vary depending on the HSE clock frequency used. > > > + > > + 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. Generally, there can also be more than two options. For example, in the case of the imx8m platform, there are three possibilities: - down-spread - center-spread - up-spread In our case, using a boolean would hide one of the two pieces of information, meaning that if I'm not using center-spread, what am I using? IMHO, I would keep the string type, changing it from on-unique-string-array to string. > > Are there dependencies between these properties? The values moddepth and modfreq are used to calculate, according to specific relationships, two values MODPER and INCSTEP, which are bit fields of a suitable register for managing the SSCG. There is a constraint between these two values, namely that MODPER * INCSTEP < 32768. This constraint will be managed at the driver level. Thanks and regards, Dario > > > + > > 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 > >
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) + + 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 + 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"; }; - |
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(+)