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From: Gergo Koteles <soyer@irl.hu>
To: med.jebabli@gmail.com, regressions@lists.linux.dev
Cc: Cristian Castellano <cristian.castellano@icloud.com>,
	stable@vger.kernel.org, Takashi Iwai <tiwai@suse.com>,
	Jaroslav Kysela <perex@perex.cz>,
	linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org,
	Thorsten Leemhuis <regressions@leemhuis.info>,
	Shenghao Ding <shenghao-ding@ti.com>, Kevin Lu <kevin-lu@ti.com>,
	Baojun Xu <baojun.xu@ti.com>, Sen Wang <sen@ti.com>
Subject: Re: [PATCH] ALSA: hda/tas2781: Only accept CRC-less V1 data if all entries are valid
Date: Wed, 04 Nov 2026 16:55:36 +0100	[thread overview]
Message-ID: <7cd4c010f13ee085e3aa4396705b6b06ed58f7e1.camel@irl.hu> (raw)
In-Reply-To: <20261103-tas2781-v1-nocrc-fix-v1-1-a769c27f21ce@gmail.com>

Hi Mohamed,

On Tue, 2026-11-03 at 10:27 +0100, Mohamed Yassine Jebabli via B4 Relay
wrote:
> From: Mohamed Yassine Jebabli <med.jebabli@gmail.com>
> 
> Commit 408249089c48 ("ALSA: hda/tas2781: Accept V1 calibration data
> without CRC") only checked the first device entry. On machines where
> the BIOS populates fewer entries than p->ndev, the remaining all-zero
> entries are applied and tas2781_cali_preproc() divides by zero on
> playback open.
> 
> Accept CRC-less V1 data only if every expected entry is non-zero and
> self-consistent (R0 * 1/R0 close to 1.0), otherwise reject it as
> before.
> 

...

>  
> +/*
> + * V1 data without CRC is only trusted if every expected device has a
> + * populated, self-consistent entry: R0 (Q27) * 1/R0 (Q31) must be
> + * close to 1.0 in Q58.
> + */

Just out of curiosity, where do Q27, Q31, Q58 come from?
I couldn't find anything about these.

Thanks,
Gergo

      parent reply	other threads:[~2026-11-04 15:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-03  9:27 Mohamed Yassine Jebabli via B4 Relay
2026-11-04  7:22 ` Takashi Iwai
2026-11-04 15:55 ` Gergo Koteles [this message]

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