diff mbox series

[v6,16/18] dt-bindings: clock: imx8m-clock: support spread spectrum clocking

Message ID 20241222170534.3621453-17-dario.binacchi@amarulasolutions.com
State New
Headers
Series Support spread spectrum clocking for i.MX8N PLLs |

Commit Message

Dario Binacchi Dec. 22, 2024, 5:04 p.m. UTC 
The addition of DT bindings for enabling and tuning spread spectrum
clocking generation can be applied specifically to the PLLs.

The "" value for the fsl,ssc-method property is specifically intended to
specify a "no SSC" case, as in the example, when you don't want to
configure spread spectrum for one of the PLLs, thus avoiding the use of
a method that would only make sense if SSC were being set.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>

---

Changes in v6:
- Improve the commit message
- change minItems from 7 to 1 for all the ssc properties added
- change maxItems from 10 to 4 for alle the ssc properties added
- update the DTS example

Changes in v4:
- Drop "fsl,ssc-clocks" property. The other added properties now refer
  to the clock list.
- Updated minItems and maxItems of
  - clocks
  - clock-names
  - fsl,ssc-modfreq-hz
  - fsl,ssc-modrate-percent
  - fsl,ssc-modmethod
- Updated the dts examples

Changes in v3:
- Added in v3
- The dt-bindings have been moved from fsl,imx8m-anatop.yaml to
  imx8m-clock.yaml. The anatop device (fsl,imx8m-anatop.yaml) is
  indeed more or less a syscon, so it represents a memory area
  accessible by ccm (imx8m-clock.yaml) to setup the PLLs.

Changes in v2:
- Add "allOf:" and place it after "required:" block, like in the
  example schema.
- Move the properties definition to the top-level.
- Drop unit types as requested by the "make dt_binding_check" command.

 .../bindings/clock/imx8m-clock.yaml           | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)

Comments

'Abel Vesa' via Amarula Linux Dec. 23, 2024, 3:05 p.m. UTC | #1 
On Sun, Dec 22, 2024 at 06:04:31PM +0100, Dario Binacchi wrote:
> The addition of DT bindings for enabling and tuning spread spectrum
> clocking generation can be applied specifically to the PLLs.
> 
> The "" value for the fsl,ssc-method property is specifically intended to
> specify a "no SSC" case, as in the example, when you don't want to
> configure spread spectrum for one of the PLLs, thus avoiding the use of
> a method that would only make sense if SSC were being set.
> 
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> 
> ---
> 
> Changes in v6:
> - Improve the commit message
> - change minItems from 7 to 1 for all the ssc properties added
> - change maxItems from 10 to 4 for alle the ssc properties added
> - update the DTS example
> 
> Changes in v4:
> - Drop "fsl,ssc-clocks" property. The other added properties now refer
>   to the clock list.
> - Updated minItems and maxItems of
>   - clocks
>   - clock-names
>   - fsl,ssc-modfreq-hz
>   - fsl,ssc-modrate-percent
>   - fsl,ssc-modmethod
> - Updated the dts examples
> 
> Changes in v3:
> - Added in v3
> - The dt-bindings have been moved from fsl,imx8m-anatop.yaml to
>   imx8m-clock.yaml. The anatop device (fsl,imx8m-anatop.yaml) is
>   indeed more or less a syscon, so it represents a memory area
>   accessible by ccm (imx8m-clock.yaml) to setup the PLLs.
> 
> Changes in v2:
> - Add "allOf:" and place it after "required:" block, like in the
>   example schema.
> - Move the properties definition to the top-level.
> - Drop unit types as requested by the "make dt_binding_check" command.
> 
>  .../bindings/clock/imx8m-clock.yaml           | 38 +++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> index 05bc01960045..37cc6a6e89d4 100644
> --- a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> +++ b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> @@ -43,6 +43,37 @@ properties:
>        ID in its "clocks" phandle cell. See include/dt-bindings/clock/imx8m-clock.h
>        for the full list of i.MX8M clock IDs.
>  
> +  fsl,ssc-modfreq-hz:
> +    description:
> +      The values of modulation frequency (Hz unit) for each clock
> +      supporting spread spectrum (i. e. audio_pll1, audio_pll2,
> +      dram_pll and video_pll).
> +    minItems: 1
> +    maxItems: 4

Please list the items. You rely here on this being in strict order, so
this should be explicit, instead of just "in example" in the
description.

items:
  - description: audio_pll1

> +
> +  fsl,ssc-modrate-percent:
> +    description:
> +      The percentage values of modulation rate for each clock
> +      supporting spread spectrum (i. e. audio_pll1, audio_pll2,
> +      dram_pll and video_pll).
> +    minItems: 1
> +    maxItems: 4

Ditto

> +
> +  fsl,ssc-modmethod:
> +    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +    description:
> +      The modulation techniques for each clock supporting spread
> +      spectrum (i. e. audio_pll1, audio_pll2, dram_pll and
> +      video_pll).

I guess here listing items might not work, so:

  The modulation techniques for each clock supporting spread
  spectrum, in this order: audio_pll1, audio_pll2, dram_pll and video_pll

Everything looks good for me, so with above changes:

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

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diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
index 05bc01960045..37cc6a6e89d4 100644
--- a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
+++ b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
@@ -43,6 +43,37 @@  properties:
       ID in its "clocks" phandle cell. See include/dt-bindings/clock/imx8m-clock.h
       for the full list of i.MX8M clock IDs.
 
+  fsl,ssc-modfreq-hz:
+    description:
+      The values of modulation frequency (Hz unit) for each clock
+      supporting spread spectrum (i. e. audio_pll1, audio_pll2,
+      dram_pll and video_pll).
+    minItems: 1
+    maxItems: 4
+
+  fsl,ssc-modrate-percent:
+    description:
+      The percentage values of modulation rate for each clock
+      supporting spread spectrum (i. e. audio_pll1, audio_pll2,
+      dram_pll and video_pll).
+    minItems: 1
+    maxItems: 4
+
+  fsl,ssc-modmethod:
+    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+    description:
+      The modulation techniques for each clock supporting spread
+      spectrum (i. e. audio_pll1, audio_pll2, dram_pll and
+      video_pll).
+    minItems: 1
+    maxItems: 4
+    items:
+      enum:
+        - ""
+        - down-spread
+        - up-spread
+        - center-spread
+
 required:
   - compatible
   - reg
@@ -76,6 +107,10 @@  allOf:
             - const: clk_ext2
             - const: clk_ext3
             - const: clk_ext4
+        fsl,ssc-modfreq-hz: false
+        fsl,ssc-modrate-percent: false
+        fsl,ssc-modmethod: false
+
     else:
       properties:
         clocks:
@@ -124,6 +159,9 @@  examples:
         clock-names = "osc_32k", "osc_24m", "clk_ext1", "clk_ext2",
                       "clk_ext3", "clk_ext4", "audio_pll1", "audio_pll2",
                       "dram_pll", "video_pll";
+        fsl,ssc-modfreq-hz = <6818>, <0>, <0>, <2419>;
+        fsl,ssc-modrate-percent = <3>, <0>, <0>, <7>;
+        fsl,ssc-modmethod = "down-spread", "", "", "center-spread";
     };
 
   - |