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ALSA: ctxfi: Fix CA20K2 S/PDIF passthrough

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dao_rsc_init() encodes the DAIO configuration as

    conf = (desc->msr & 0x7) | (desc->passthru << 3);

S/PDIF passthrough uses msr=1 and passthru=1, resulting in
conf=9.

daio_mgr_dao_init() masks conf with 0xf, but handles only values
1, 2, 4 and 8 when programming ATXCTL_NUC. As a result, conf=9
falls through to the default case and leaves NUC at its previous
setting.

On a Creative X-Fi Titanium HD SB1270 (CA20K2), this breaks AC3
IEC61937 passthrough when snd_ctxfi runs with
reference_rate=48000,multiple=2. The receiver detects a non-audio
stream but cannot decode the AC3 payload.

With the unmodified driver, multiple=1 makes the same stream work.
Handle conf=9 through the same NUC=0 path as conf=1.

The change was runtime tested on the SB1270 with multiple=2 using
IEC958 stereo PCM, pre-encoded AC3 IEC61937 passthrough and ALSA
A52 live 5.1 encoding.

Fixes: 26a9630c72 ("ALSA: ctxfi: cthw20k2: fix mask on conf to allow 4 bits")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Roman Prucha <zorgan.roman@gmail.com>
Link: https://patch.msgid.link/20260903-ctxfi-spdif-conf9-fix-v1-1-5e4e3e1f801c@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Roman Prucha 2026-09-03 23:14:44 +02:00 committed by Takashi Iwai
parent 9fe49dbc02
commit b26a7a80e6
1 changed files with 1 additions and 0 deletions
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1
sound/pci/ctxfi/cthw20k2.c
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@ -994,6 +994,7 @@ static int daio_mgr_dao_init(struct hw *hw, void *blk, unsigned int idx, unsigne
/* S/PDIF output */
switch ((conf & 0xf)) {
case 1:
case 9:
set_field(&ctl->txctl[idx], ATXCTL_NUC, 0);
break;
case 2: