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Message-ID: <752f5347-703a-4b38-b2b1-3493d270389c@linaro.org>
Date: Tue, 28 Nov 2023 10:14:29 +0100
From: neil.armstrong@...aro.org
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Banajit Goswami <bgoswami@...cinc.com>,
Andy Gross <agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
Cc: linux-arm-msm@...r.kernel.org, alsa-devel@...a-project.org,
linux-sound@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] ASoC: dt-bindings: document WCD939x Audio Codec
On 28/11/2023 10:04, Krzysztof Kozlowski wrote:
> On 28/11/2023 09:59, Neil Armstrong wrote:
>> On 24/11/2023 09:33, Krzysztof Kozlowski wrote:
>>> On 23/11/2023 15:49, Neil Armstrong wrote:
>>>
>>>> + Qualcomm WCD9390/WCD9395 Codec is a standalone Hi-Fi audio codec IC.
>>>> + It has RX and TX Soundwire slave devices.
>>>> + The WCD9390/WCD9395 IC has a functionally separate USB-C Mux subsystem
>>>> + accessible over an I2C interface.
>>>> + The Audio Headphone and Microphone data path between the Codec and the USB-C Mux
>>>> + subsystems are external to the IC, thus requiring DT port-endpoint graph description
>>>> + to handle USB-C altmode & orientation switching for Audio Accessory Mode.
>>>> +
>>>> +allOf:
>>>> + - $ref: dai-common.yaml#
>>>> + - $ref: qcom,wcd93xx-common.yaml#
>>>> +
>>>> +properties:
>>>> + compatible:
>>>> + enum:
>>>> + - qcom,wcd9390-codec
>>>> + - qcom,wcd9395-codec
>>>
>>> 9395 should be compatible with 9390, so please express it with a list
>>> using fallback. I know that earlier wcd93xx do not follow that concept,
>>> but maybe we will fix them some point as well.
>>
>> I don't get why this would be needed, yes their are compatible but still
>> two separate ICs with different internal capabilities.
>>
>> It the first time I get such request for new documentation
>
> Maybe it is first time for you, but I ask about this all the time. What
> is important is whether the programming model or how the OS uses the
> device is the same.
I agree for new version of HW, anyway..
>
> Here the device exposes its version in registers, so you can easily rely
> on the compatibility. That's also the case multiple times talked on the
> mailing lists.
... you're right here version can be determined at runtime.
But, since both are compatible, there's no primary part number, right?
so why use "qcom,wcd9395-codec", "qcom,wcd9390-codec"
when "qcom,wcd9390-codec", "qcom,wcd9395-codec" should
also be valid, so in this can why not use :
"qcom,wcd9390-codec", "qcom,wcd939x-codec"
or
"qcom,wcd9395-codec", "qcom,wcd939x-codec"
?
>
> Best regards,
> Krzysztof
>
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