Re: [PATCH v2 1/4] ASoC: dt-bindings: wcd937x-sdw: Add static channel mapping support

[Krzysztof Kozlowski <krzk@xxxxxxxxxx>]

On 23/10/2024 09:52, Krzysztof Kozlowski wrote:
> On Wed, Oct 23, 2024 at 11:43:23AM +0530, Mohammad Rafi Shaik wrote:
>> Add static channel mapping between master and slave rx/tx ports for
>> Qualcomm wcd937x soundwire codec.
>>
>> Currently, the channel mask for each soundwire port is hardcoded in the
>> wcd937x-sdw driver, and the same channel mask value is configured in the
>> soundwire master.
>>
>> The Qualcomm boards like the QCM6490-IDP require different channel mask settings
>> for the soundwire master and slave ports.
> 
> Different than what? Other wcd937x? Which are these?
> 
>>
>> With the introduction of the following channel mapping properties, it is now possible
>> to configure the master channel mask directly from the device tree.
>>
>> The qcom,tx-channel-mapping property specifies the static channel mapping between the slave
>> and master tx ports in the order of slave port channels which is adc1, adc2, adc3, adc4,
>> dmic0, dmic1, mbhc, dmic2, dmic3, dmci4, dmic5, dmic6, dmic7.
> 
> I still don't get what is the channel here.
> 
>>
>> The qcom,rx-channel-mapping property specifies static channel mapping between the slave
>> and master rx ports in the order of slave port channels which is hph_l, hph_r, clsh,
>> comp_l, comp_r, lo, dsd_r, dsd_l.
> 
> And this description copies binding :/.
> 
> Please wrap commit message according to Linux coding style / submission
> process (neither too early nor over the limit):
> https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/process/submitting-patches.rst#L597
> 
>>
>> Signed-off-by: Mohammad Rafi Shaik <quic_mohs@xxxxxxxxxxx>
>> ---
>>  .../bindings/sound/qcom,wcd937x-sdw.yaml      | 36 +++++++++++++++++++
>>  1 file changed, 36 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/sound/qcom,wcd937x-sdw.yaml b/Documentation/devicetree/bindings/sound/qcom,wcd937x-sdw.yaml
>> index d3cf8f59cb23..a6bc9b391db0 100644
>> --- a/Documentation/devicetree/bindings/sound/qcom,wcd937x-sdw.yaml
>> +++ b/Documentation/devicetree/bindings/sound/qcom,wcd937x-sdw.yaml
>> @@ -58,6 +58,38 @@ properties:
>>      items:
>>        enum: [1, 2, 3, 4, 5]
>>  
>> +  qcom,tx-channel-mapping:
>> +    description: |
>> +      Specifies static channel mapping between slave and master tx port
>> +      channels.
>> +      In the order of slave port channels which is adc1, adc2, adc3, adc4,
>> +      dmic0, dmic1, mbhc, dmic2, dmic3, dmci4, dmic5, dmic6, dmic7.
>> +      ch_mask1 ==> bit mask value 1
>> +      ch_mask2 ==> bit mask value 2
>> +      ch_mask3 ==> bit mask value 4
>> +      ch_mask4 ==> bit mask value 8
>> +    $ref: /schemas/types.yaml#/definitions/uint8-array
>> +    minItems: 8
>> +    maxItems: 13
> 
> Why size is variable? This device has fixed amount of slave ports, I
> think.
> 
>> +    items:
>> +      enum: [1, 2, 4, 8]
> 
> What is the point of using bits if you cannot actually create a bit mask
> out of it? Why this cannot be 7?
> 
>> +
>> +  qcom,rx-channel-mapping:
>> +    description: |
>> +      Specifies static channels mapping between slave and master rx port
>> +      channels.
>> +      In the order of slave port channels, which is
>> +      hph_l, hph_r, clsh, comp_l, comp_r, lo, dsd_r, dsd_l.
>> +      ch_mask1 ==> bit mask value 1
>> +      ch_mask2 ==> bit mask value 2
>> +      ch_mask3 ==> bit mask value 4
>> +      ch_mask4 ==> bit mask value 8
> 
> and the value is what exactly? Index is channel, but what does "ch_mask4 ==> bit
> mask value 8" mean? I don't understand this at all.

Ah, and previous feedback was to use strings, no?

Best regards,
Krzysztof