linux-kernel - Re: [EXTERNAL] Re: [PATCH v2 2/5] ASoC: dt-bindings: Add tas2781 amplifier

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Date:   Wed, 17 May 2023 17:05:42 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     "Ding, Shenghao" <shenghao-ding@...com>,
        Mark Brown <broonie@...nel.org>
Cc:     Shenghao Ding <13916275206@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "pierre-louis.bossart@...ux.intel.com" 
        <pierre-louis.bossart@...ux.intel.com>,
        "Lu, Kevin" <kevin-lu@...com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Xu, Baojun" <x1077012@...com>, "Gupta, Peeyush" <peeyush@...com>,
        "Navada Kanyana, Mukund" <navada@...com>,
        "gentuser@...il.com" <gentuser@...il.com>,
        "Ryan_Chu@...tron.com" <Ryan_Chu@...tron.com>,
        "Sam_Wu@...tron.com" <Sam_Wu@...tron.com>
Subject: Re: [EXTERNAL] Re: [PATCH v2 2/5] ASoC: dt-bindings: Add tas2781
 amplifier

On 17/05/2023 14:24, Ding, Shenghao wrote:
> 
> 
> On 11/05/2023 15:19, Ding, Shenghao wrote:
>>
>> On 11/05/2023 07:49, Mark Brown wrote:
>>>> Missing minItems, but...
>>>
>>>>> +    items:
>>>>> +      minimum: 0x38
>>>>> +      maximum: 0x3f
>>>
>>>> ... So these are fixed? No need to encode them in such case...
>>>
>>> I'm not sure I understand your concern here, there's up to 4 possible 
>>> values from 0x38-0x3f which has more than 4 possible values.
>>
>> Aren't the addresses going to be incremented by one (up to 8 of devices in total)?
> 
> With your style of replies, it looks like you wrote it...
> 
> All the addresses of tas2781 are in range from 0x38 to 0x 3f, the order of them in the audio-slots item are up to the hardware connections.
> I have studied the reg item to save multiple i2c addresses for multiple pieces of tas2781 and found that "'#address-cells':     maximum: 3"
> that means "reg" store not more than three addresses, this can't support the more than 3 pieces of tas2781, 

No entirely. This determines the size of each address, not the number of
addresses.

> such as 4-slot TDM case or multiple dual-membrane speakers case, in such a case, one speaker will use
>  two pieces of tas2781 to boost, usually at least 6 pieces of tas2781 will be used in a laptop or other device.
> 
>>
>> No, the i2c address order is not always monotonic increase or decrease, sometime it would be disorder, according to the application.
>> Each device would have eight possible i2c address, the final address depends on the hardware connections.
> 
> OK, the question about the broadcast is still there - cannot it be deduced?
> 
> The reason to define this item and add it in dts is that tell tas2781 driver code to enable broadcast and its address. 
> Removing this item means disabling broadcast. Do you want to hardcode the global address in the code?
> And this item only used as a flag to enable or disable?
> 
> Best regards,
> Krzysztof
> 

Hi Krzysztof, nice to talk with you!

I really do not know what is here mine what's yours. I could guess, but
we are all a bit busy, so I would appreciate if reading your email was
easier for me.

Best regards,
Krzysztof