linux-kernel - Re: [PATCH 1/2] ASoC: codecs: wsa883x: do not set can_multi

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Message-ID: <af7b7d4f-d7ab-b5ef-e639-9a8b13de54ee@linaro.org>
Date:   Wed, 24 May 2023 10:42:21 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     perex@...ex.cz, tiwai@...e.com, lgirdwood@...il.com,
        ckeepax@...nsource.cirrus.com, kuninori.morimoto.gx@...esas.com,
        linux-kernel@...r.kernel.org, pierre-louis.bossart@...ux.intel.com,
        alsa-devel@...a-project.org
Subject: Re: [PATCH 1/2] ASoC: codecs: wsa883x: do not set can_multi_write
 flag

On 24/05/2023 09:57, Mark Brown wrote:
> On Wed, May 24, 2023 at 09:51:00AM +0100, Srinivas Kandagatla wrote:
>> On 23/05/2023 17:55, Mark Brown wrote:
> 
>>> Does the CODEC support mulitple writes?  If so it seems better to leave
> 
>> No, the codec itself does not support multi-write. All the codec register
>> level interface is via SoundWire Bus. which also does not support with the
>> existing code.
> 
> I'm unclear, is this a limitation of the hardware or of the current
> Soundwire code?

Its both.

Codec itself does not have any private write callback to support this 
and AFAIU Qualcomm Soundwire controller does not have any such hw 
facility to program multi-registers for device at one shot.

Also to note, the current state of code soundwire regmap write callback 
assumes that the request to write will always have base address at the 
start followed by register values. This is not true for multi-register 
writes which comes in address-value-padding pairs.

Am confused on the multi_write feature and looking at regmap bus level 
write callback.

Is write callback used for both Bulk writes and multi-writes?

Is multi-write feature of regmap bus or device?

--srini