linux-kernel - Re: [PATCH v1] ALSA: hda/tas2781: Prevent throwing away custom calibration addresses

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Message-ID: 
 <CAGwozwGXCe-nDi7moPvPH++_Bz687Ksffe1GU37qcTxR2ygx+g@mail.gmail.com>
Date: Wed, 7 Jan 2026 12:21:58 +0200
From: Antheas Kapenekakis <lkml@...heas.dev>
To: Matthew Schwartz <matthew.schwartz@...ux.dev>
Cc: Shenghao Ding <shenghao-ding@...com>, Baojun Xu <baojun.xu@...com>,
 tiwai@...e.de,
	linux-kernel@...r.kernel.org, linux-sound@...r.kernel.org
Subject: Re: [PATCH v1] ALSA: hda/tas2781: Prevent throwing away custom
 calibration addresses

On Wed, 7 Jan 2026 at 12:17, Matthew Schwartz
<matthew.schwartz@...ux.dev> wrote:
>
>
>
> > On Jan 7, 2026, at 1:32 AM, Antheas Kapenekakis <lkml@...heas.dev> wrote:
> >
> > The V2 UEFI spec for per-device calibration data in TAS allows for
> > manufacturers to specify up to five custom calibration register
> > addresses and values to optimize per-device in factory.
> >
> > A basic description of the spec is found in a comment in function
> > tas2781_apply_calib(). However, currently, for the condition of
> > p->dspbin_typ != TASDEV_BASIC, if custom calibration addresses have been
> > provided by the manufacturer, they are ignored and the ones listed in
> > firmware are used.
> >
> > In case the manufacturer chose to change different registers other than
> > the default ones (r0, invr0, r0_low, pow, tlimit), this causes the
> > UEFI calibration data to scratch different registers and cause the
> > firmware to misbehave. This is true in the Xbox ROG Ally X, for one of
> > the firmwares, where it pops and has audio dropouts after the
> > calibration data is applied.
> >
> > Therefore, add a new bool to indicate that UEFI supplied custom
> > calibration addresses, and if so, use them regardless of dspbin_typ.
> >
> > Link: https://lore.kernel.org/all/CAGwozwFQKoQgo_Q=qdr-FTD+uoVWA8AtHyDmKwTOV4ZU6+F3SQ@mail.gmail.com/
> > Reported-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
> > Closes: https://lore.kernel.org/all/0ba100d0-9b6f-4a3b-bffa-61abe1b46cd5@linux.dev/
> > Co-developed-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
> > Signed-off-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
> > Signed-off-by: Antheas Kapenekakis <lkml@...heas.dev>
> >
> > ---
> > @Matt: can you kindly verify this patch works for you?
>
> I’ll have time to debug it more in the morning but the patch does not work, it’s still using the same calibrated data as before with dropouts.

If you can check that the register addresses changed that would be
great. Especially that we enter and exit the calibration block.
Perhaps that was happening before as well and the addresses were
overwritten by firmware later

Antheas

> >
> > Then verify your sign-off for the coby tag. If you would rather a
> > different acknowledgment tag (e.g., tested-by or suggested-by), lmk
> >
> > Thanks.
> > Antheas
> > ---
> > sound/hda/codecs/side-codecs/tas2781_hda.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/sound/hda/codecs/side-codecs/tas2781_hda.c b/sound/hda/codecs/side-codecs/tas2781_hda.c
> > index 96e6d82dc69e..6efdf0a3442b 100644
> > --- a/sound/hda/codecs/side-codecs/tas2781_hda.c
> > +++ b/sound/hda/codecs/side-codecs/tas2781_hda.c
> > @@ -64,6 +64,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
> >       TASDEVICE_REG(0, 0x18, 0x7c),
> >   };
> >   unsigned int crc, oft, node_num;
> > +    bool custom_addr = false;
> >   unsigned char *buf;
> >   int i, j, k, l;
> >
> > @@ -104,6 +105,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
> >       for (j = 0, k = 0; j < node_num; j++) {
> >           oft = j * 6 + 3;
> >           if (tmp_val[oft] == TASDEV_UEFI_CALI_REG_ADDR_FLG) {
> > +                custom_addr = true;
> >               for (i = 0; i < TASDEV_CALIB_N; i++) {
> >                   buf = &data[(oft + i + 1) * 4];
> >                   cali_reg[i] = TASDEVICE_REG(buf[1],
> > @@ -151,7 +153,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
> >       }
> >   }
> >
> > -    if (p->dspbin_typ == TASDEV_BASIC) {
> > +    if (custom_addr || p->dspbin_typ == TASDEV_BASIC) {
> >       r->r0_reg = cali_reg[0];
> >       r->invr0_reg = cali_reg[1];
> >       r->r0_low_reg = cali_reg[2];
> >
> > base-commit: 9ace4753a5202b02191d54e9fdf7f9e3d02b85eb
> > --
> > 2.52.0
>