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Date:   Wed, 24 May 2023 11:09:32 +0100
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Subject: Re: [PATCH 1/2] ASoC: codecs: wsa883x: do not set can_multi_write
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To:     Mark Brown <broonie@kernel.org>
Cc:     perex@perex.cz, tiwai@suse.com, lgirdwood@gmail.com,
        ckeepax@opensource.cirrus.com, kuninori.morimoto.gx@renesas.com,
        linux-kernel@vger.kernel.org, pierre-louis.bossart@linux.intel.com,
        alsa-devel@alsa-project.org
References: <20230523154605.4284-1-srinivas.kandagatla@linaro.org>
 <00283665-e44f-457b-b2c9-1acf59d1cbd8@sirena.org.uk>
 <c37b88ae-7f54-3c07-666f-010a5fd84bd1@linaro.org>
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 <af7b7d4f-d7ab-b5ef-e639-9a8b13de54ee@linaro.org>
 <c24b2f1c-3b08-492f-954c-c4f10ae5ad81@sirena.org.uk>
From:   Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
In-Reply-To: <c24b2f1c-3b08-492f-954c-c4f10ae5ad81@sirena.org.uk>
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On 24/05/2023 10:48, Mark Brown wrote:
> On Wed, May 24, 2023 at 10:42:21AM +0100, Srinivas Kandagatla wrote:
>> On 24/05/2023 09:57, Mark Brown wrote:
> 
>>> 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.
> 
> How about the *CODEC* hardware?
> 
No, Codec does not have any such interface to write to device registers 
directly without going via Soundwire.

>> Is write callback used for both Bulk writes and multi-writes?
> 
> Only multi-write at this point but we probably should consider redoing
> bulk writes to use it as well.

By the looks of the code, its other way around.

> 
>> Is multi-write feature of regmap bus or device?
> 
> Well, I don't think any buses that understand registers have implemented
> it yet but there's nothing fundamental that means that a bus couldn't
> usefully do something with multi-write.  The current users all use raw
> buses that don't know anything about registers or values.