linux-kernel - Re: [PATCH v9 16/23] dt-bindings: clock: imx8m-clock: support spread spectrum clocking

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Message-ID: <1d4b7179-754c-4297-a847-798b96d2b82f@kernel.org>
Date: Fri, 24 Jan 2025 14:43:45 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Dario Binacchi <dario.binacchi@...rulasolutions.com>,
 linux-kernel@...r.kernel.org
Cc: linux-amarula@...rulasolutions.com,
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
 Abel Vesa <abelvesa@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
 Fabio Estevam <festevam@...il.com>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Michael Turquette <mturquette@...libre.com>,
 Peng Fan <peng.fan@....com>, Pengutronix Kernel Team
 <kernel@...gutronix.de>, Rob Herring <robh@...nel.org>,
 Sascha Hauer <s.hauer@...gutronix.de>, Shawn Guo <shawnguo@...nel.org>,
 Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 linux-clk@...r.kernel.org
Subject: Re: [PATCH v9 16/23] dt-bindings: clock: imx8m-clock: support spread
 spectrum clocking

On 18/01/2025 13:39, 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@...rulasolutions.com>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> 
> ---
> 
> (no changes since v7)
> 
> Changes in v7:
> - List the PLLs to strictly define the setup order for each of the
>   added properties
> - Drop maxItems from "fsl,ssc-modfreq-hz" and "fsl,ssc-modrate-percent"
>   properties
> - Add 'Reviewed-by' tag of Krzysztof Kozlowski
> 
> 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           | 47 +++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> index d96570bf60dc..d347d630764a 100644
> --- a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> +++ b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> @@ -43,6 +43,46 @@ 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.
> +    minItems: 1
> +    items:
> +      - description: audio_pll1
> +      - description: audio_pll2
> +      - description: dram_pll
> +      - description: video_pll

Ehh, so it looks that nine versions of this patches for iMX8 and NXP
comes with generic bindings for iMX9.

Better late than never, but a pity that they did not share the
intention, which would spare you effort.

Please work with Peng and unify approach for entire iMX and use common
bindings.

https://github.com/devicetree-org/dt-schema/pull/154

Best regards,
Krzysztof