linux-kernel - Re: [PATCH v2] ALSA: hda/tas2781: Fix the order of TAS2781 calibrated-data

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Message-ID: <875xdzx5nn.wl-tiwai@suse.de>
Date: Wed, 03 Sep 2025 11:10:52 +0200
From: Takashi Iwai <tiwai@...e.de>
To: Shenghao Ding <shenghao-ding@...com>
Cc: <broonie@...nel.org>,
	<andriy.shevchenko@...ux.intel.com>,
	<13564923607@....com>,
	<13916275206@....com>,
	<alsa-devel@...a-project.org>,
	<linux-kernel@...r.kernel.org>,
	<baojun.xu@...com>,
	<Baojun.Xu@....com>
Subject: Re: [PATCH v2] ALSA: hda/tas2781: Fix the order of TAS2781 calibrated-data

On Wed, 03 Sep 2025 06:13:51 +0200,
Shenghao Ding wrote:
> 
> A bug reported by one of my customers that the order of TAS2781
> calibrated-data is incorrect, the correct way is to move R0_Low
> and insert it between R0 and InvR0.
> 
> Fixes: 4fe238513407 ("ALSA: hda/tas2781: Move and unified the calibrated-data getting function for SPI and I2C into the tas2781_hda lib")
> Signed-off-by: Shenghao Ding <shenghao-ding@...com>
> 
> ---
> v2:
>  - Submit to sound branch maintianed by Tiwai instead of linux-next branch
>  - drop other fix
> ---
>  sound/hda/codecs/side-codecs/tas2781_hda.c | 38 ++++++++++++++++++----
>  1 file changed, 32 insertions(+), 6 deletions(-)
> 
> diff --git a/sound/hda/codecs/side-codecs/tas2781_hda.c b/sound/hda/codecs/side-codecs/tas2781_hda.c
> index f46d2e06c64f..cd9990869e18 100644
> --- a/sound/hda/codecs/side-codecs/tas2781_hda.c
> +++ b/sound/hda/codecs/side-codecs/tas2781_hda.c
> @@ -33,6 +33,32 @@ const efi_guid_t tasdev_fct_efi_guid[] = {
>  };
>  EXPORT_SYMBOL_NS_GPL(tasdev_fct_efi_guid, "SND_HDA_SCODEC_TAS2781");
>  
> +/*
> + * The order of calibrated-data writing is a bit different from the order
> + * in UEFI. Here is the conversion to match the order of calibrated-data
> + * writing.
> + */
> +static void cali_cnv(unsigned char *data, unsigned int base, int offset)
> +{
> +	__be32 bedata[TASDEV_CALIB_N];
> +	int i;
> +
> +	/* r0_reg */
> +	bedata[0] = cpu_to_be32(*(uint32_t *)&data[base]);
> +	/* r0_low_reg */
> +	bedata[1] = cpu_to_be32(*(uint32_t *)&data[base + 8]);
> +	/* invr0_reg */
> +	bedata[2] = cpu_to_be32(*(uint32_t *)&data[base + 4]);
> +	/* pow_reg */
> +	bedata[3] = cpu_to_be32(*(uint32_t *)&data[base + 12]);
> +	/* tlimit_reg */
> +	bedata[4] = cpu_to_be32(*(uint32_t *)&data[base + 16]);
> +
> +	for (i = 0; i < TASDEV_CALIB_N; i++)
> +		memcpy(&data[offset + i * 4 + 1], &bedata[i],
> +			sizeof(bedata[i]));
> +}

IMO, this can be more readable when you use struct calidata, e.g.

static void cali_cnv(unsigned char *data, unsigned int base, int offset)
{
	struct calidata reg;

	reg.r0_reg = *(u32 *)&data[base]
	reg.r0_low_reg = *(u32 *)&data[base + 8]
	reg.invr0_reg = *(u32 *)&data[base + 4]
	reg.pow_reg = *(u32 *)&data[base + 12];
	reg.tlimit_reg = *(u32 *)&data[base + 16]);

	cpu_to_be32_array((__force __be32 *)(data + offset + 1), &reg,
			  TASDEV_CALIB_N);
}

... or even simpler like:

static void cali_cnv(unsigned char *data, unsigned int base, int offset)
{
	struct calidata reg;

	memcpy(&reg, data, sizeof(reg));
	/* the data order has to be swapped between r0_low_reg and inv0_reg */
	swap(reg.r0_low_reg, reg.invr0_reg);

	cpu_to_be32_array((__force __be32 *)(data + offset + 1), &reg,
			  TASDEV_CALIB_N);
}

>  static void tas2781_apply_calib(struct tasdevice_priv *p)
>  {
>  	struct calidata *cali_data = &p->cali_data;
> @@ -86,6 +112,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
>  
>  		for (j = 0, k = 0; j < node_num; j++) {
>  			oft = j * 6 + 3;
> +			/* Calibration registers address */

Don't try to add unrelated changes.  This comment won't fix or explain
what your patch does.  If any, make another patch to update / add more
comments.
Putting unrelated changes disturbs the patch readability *a lot*

>  			if (tmp_val[oft] == TASDEV_UEFI_CALI_REG_ADDR_FLG) {
>  				for (i = 0; i < TASDEV_CALIB_N; i++) {
>  					buf = &data[(oft + i + 1) * 4];
> @@ -93,6 +120,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
>  						buf[2], buf[3]);
>  				}
>  			} else {
> +				/* Calibrated data */

Ditto.

> @@ -127,12 +154,11 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
>  			dev_err(p->dev, "%s: V1 CRC error\n", __func__);
>  			return;
>  		}
> -
> +		/* reverse rearrangement in case of overlap */

Ditto.


thanks,

Takashi