linux-kernel - Re: [PATCH v2 2/2] dt-bindings: dsp: fsl: Add DSP optional clocks documentation

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Date:   Fri, 3 Sep 2021 11:53:43 -0500
From:   Rob Herring <robh@...nel.org>
To:     Daniel Baluta <daniel.baluta@....nxp.com>
Cc:     broonie@...nel.org, pierre-louis.bossart@...ux.intel.com,
        lgirdwood@...il.com, ranjani.sridharan@...ux.intel.com,
        kai.vehmanen@...ux.intel.com, devicetree@...r.kernel.org,
        shawnguo@...nel.org, kernel@...gutronix.de, festevam@...il.com,
        linux-imx@....com, peter.ujfalusi@...ux.intel.com,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        s-anna@...com, Daniel Baluta <daniel.baluta@....com>
Subject: Re: [PATCH v2 2/2] dt-bindings: dsp: fsl: Add DSP optional clocks
 documentation

On Fri, Sep 03, 2021 at 05:53:40PM +0300, Daniel Baluta wrote:
> From: Daniel Baluta <daniel.baluta@....com>
> 
> DSP node on the Linux kernel side must also take care of enabling
> DAI/DMA related clocks.
> 
> By design we choose to manage DAI/DMA clocks from the kernel side because of
> the architecture of some i.MX8 boards.
> 
> Clocks are handled by a special M4 core which runs a special firmware
> called SCFW (System Controler firmware).
> 
> This communicates with A cores running Linux via a special Messaging
> Unit and implements a custom API which is already implemented by the
> Linux kernel i.MX clocks implementation.
> 
> Note that these clocks are optional. We can use the DSP without them.
> 
> Signed-off-by: Daniel Baluta <daniel.baluta@....com>
> ---
>  .../devicetree/bindings/dsp/fsl,dsp.yaml      | 33 +++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml b/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml
> index 7afc9f2be13a..1453668c0194 100644
> --- a/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml
> +++ b/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml
> @@ -24,16 +24,49 @@ properties:
>      maxItems: 1
>  
>    clocks:
> +    minItems: 3
>      items:
>        - description: ipg clock
>        - description: ocram clock
>        - description: core clock
> +      - description: esai0 core clock for accessing registers
> +      - description: esai0 baud clock
> +      - description: esai0 system clock
> +      - description: esai0 spba clock required when ESAI is placed in slave mode
> +      - description: SAI1 bus clock
> +      - description: SAI1 master clock 0
> +      - description: SAI1 master clock 1
> +      - description: SAI1 master clock 2
> +      - description: SAI1 master clock 3
> +      - description: SAI3 bus clock
> +      - description: SAI3 master clock 0
> +      - description: SAI3 master clock 1
> +      - description: SAI3 master clock 2
> +      - description: SAI3 master clock 3
> +      - description: SDMA3 root clock used for accessing registers

Sigh, I just rejected this kind of thing for the other i.MX8 DSP 
binding[1].

Add a reference to the h/w block and then get the clocks (and other 
resources) from there.

Rob

[1] https://lore.kernel.org/linux-devicetree/YTDq%2FkWFPLHUnHMN@robh.at.kernel.org/