linux-kernel - Re: [PATCH v2] ASoC: tas2783: Add source files for tas2783 soundwire driver

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Date:   Thu, 17 Aug 2023 16:12:39 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     Baojun Xu <baojun.xu@...com>, lgirdwood@...il.com, perex@...ex.cz,
        tiwai@...e.com, shenghao-ding@...com, kevin-lu@...com,
        krzysztof.kozlowski@...aro.org, rf@...nsource.cirrus.com,
        shumingf@...ltek.com, herve.codina@...tlin.com,
        povik+lin@...ebit.org, ryans.lee@...log.com,
        ckeepax@...nsource.cirrus.com, sebastian.reichel@...labora.com,
        fido_max@...ox.ru, wangweidong.a@...nic.com,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        peeyush@...com, navada@...com, tiwai@...e.de,
        mengdong.lin@...el.com
Subject: Re: [PATCH v2] ASoC: tas2783: Add source files for tas2783 soundwire
 driver

On Thu, Aug 17, 2023 at 09:17:50AM -0500, Pierre-Louis Bossart wrote:

> > +		goto out;
> > +	}
> > +	/* Read the primary device as the whole */
> 
> I can't figure out what this comment means

It's part of...

> > +		dev_err(tas_dev->dev, "%s, regmap doesn't exist.\n",
> > +			__func__);
> > +		return -EINVAL;
> > +	}
> > +	/* Read the primary device */
> 
> What is a primary device?

...a thing where they're trying to present multiple devices as a unified
device with grouped control, it looks like there's some hardware support
for this.

> > +	/* Failed got calibration data from EFI. */

> I don't get what the dependency on EFI is. First time I see a codec
> needing this.

> Please describe in details what you are trying to accomplish.

It seems fairly normal to store calibration details in the device
firmware?

> > +	if (crc == tmp_val[21]) {
> > +		time64_to_tm(tmp_val[20], 0, tm);
> > +		dev_dbg(tas_priv->dev, "%4ld-%2d-%2d, %2d:%2d:%2d\n",
> > +			tm->tm_year, tm->tm_mon, tm->tm_mday,
> > +			tm->tm_hour, tm->tm_min, tm->tm_sec);

> What is this about? Why would a codec care about time?

I can see someone finding it helpful to confirm when the calibration data
that got applied was generated to make sure they're testing/using what
they thought they were.

> In addition, it's rather surprising that on attachment there is not a
> single regmap access?

Don't know if there's something different with Soundwire but for I2C/SPI
devices it's a reasonable pattern to only actually start initialising
the registers when the device actually becomes active.  Not checked that
this is actually happening.

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