linux-kernel - Re: [PATCH 1/2] ASoC: dt-bindings: fsl,mqs: Add i.MX95 platform support

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Date: Mon, 20 May 2024 12:47:35 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Shengjiu Wang <shengjiu.wang@....com>, lgirdwood@...il.com,
 broonie@...nel.org, robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
 conor+dt@...nel.org, shengjiu.wang@...il.com, linux-sound@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 Xiubo.Lee@...il.com, festevam@...il.com, nicoleotsuka@...il.com,
 perex@...ex.cz, tiwai@...e.com, alsa-devel@...a-project.org,
 linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 1/2] ASoC: dt-bindings: fsl,mqs: Add i.MX95 platform
 support

On 17/05/2024 11:45, Shengjiu Wang wrote:
> In order to support the MQS module on i.MX95, a new property
> "fsl,mqs-ctrl" needs to be added, as there are two MQS instances
> on the i.MX95 platform, the definition of bit positions in the
> control register is different. This new property is to distinguish
> these two instances.
> 
> Without this property, the difference of platforms except the
> i.MX95 was handled by the driver itself. But this new property can
> also be used for previous platforms.
> 
> The MQS only has one control register, the register may be
> in General Purpose Register memory space, or MQS its own
> memory space, or controlled by System Manager.
> The bit position in the register may be different for each
> platform, there are four parts (bits for module enablement,
> bits for reset, bits for oversampling ratio, bits for divider ratio).
> This new property includes all these things.

..

>  
>    clocks:
>      minItems: 1
> @@ -45,6 +46,22 @@ properties:
>    resets:
>      maxItems: 1
>  
> +  fsl,mqs-ctrl:
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 6
> +    maxItems: 6
> +    description: |
> +      Contains the control register information, defined as,
> +      Cell #1: register type
> +               0 - the register in owned register map
> +               1 - the register in general purpose register map
> +               2 - the register in control of system manager
> +      Cell #2: offset of the control register from the syscon
> +      Cell #3: shift bits for module enable bit
> +      Cell #4: shift bits for reset bit
> +      Cell #5: shift bits for oversampling ratio bit
> +      Cell #6: shift bits for divider ratio control bit

Thanks for detailed explanation in commit msg, but no, please do not
describe layout of registers in DTS. For the syscon phandles, you can
pass an argument (although not 6 arguments...). Usually this is enough.
For some cases, like you have differences in capabilities of this device
or its programming model, maybe you need different compatible.

If these are different capabilities, sometimes new properties are
applicable (describing hardware, not register bits...).

Best regards,
Krzysztof