linux-kernel - Re: [PATCH v3 6/6] ASoC: qdsp6: dt-bindings: Add q6afe pcm dt binding documentation

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Message-ID: <d4e16b7944adbd8859c8287673da3417@serbinski.com>
Date:   Wed, 12 Feb 2020 07:07:56 -0500
From:   Adam Serbinski <adam@...binski.com>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     Mark Brown <broonie@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Patrick Lai <plai@...eaurora.org>,
        Banajit Goswami <bgoswami@...eaurora.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 6/6] ASoC: qdsp6: dt-bindings: Add q6afe pcm dt binding
 documentation

On 2020-02-12 06:43, Srinivas Kandagatla wrote:
> On 12/02/2020 11:01, Adam Serbinski wrote:
>>>> 
>>>> +
>>>> + - qcom,pcm-slot-mapping
>>>> +    Usage: required for pcm interface
>>> 
>>> Are these not specific to 8k and 16k mode ?
>>> We should probably list values for both modes here.
>> 
>> No, this is just the offset that the audio sample is placed in with 
>> respect to a maximum of 4 slots, 16 bits wide, beginning with the sync 
>> pulse.
> 
> 
> That's not true atleast by the QDSP documentation,
> according to it we will use more slots to transfer at higher sample 
> rate. ex:
> 16 kHz data can be transferred using 8 kHz samples in two
> slots.
> 
> Also there are 32 slots for each of 4 supported channels for PCM AFE 
> port.

Ok, if that's the case, then it sounds like someone else is going to 
have to implement it. I have no way to test that kind of a 
configuration, so attempting to implement it would be futile.

> 
> 
>> 
>> When switching between 8 and 16k sample rate, it is just the sync 
>> pulse rate that is changed. The audio sample will be delivered in the 
>> same slot, just at a different frequency.