ALSA: ctxfi: Add fallback to default RSR for S/PDIF

commit 7d61662 upstream.

spdif_passthru_playback_get_resources() uses atc->pll_rate as the RSR
for the MSR calculation loop. However, pll_rate is only updated in
atc_pll_init() and not in hw_pll_init(), so it remains 0 after the
card init.

When spdif_passthru_playback_setup() skips atc_pll_init() for
32000 Hz, (rsr * desc.msr) always becomes 0, causing the loop to spin
indefinitely.

Add fallback to use atc->rsr when atc->pll_rate is 0. This reflects
the hardware state, since hw_card_init() already configures the PLL
to the default RSR.

Fixes: 8cc7236 ("ALSA: SB X-Fi driver merge")
Cc: stable@vger.kernel.org
Signed-off-by: Harin Lee <me@harin.net>
Link: https://patch.msgid.link/20260406074913.217374-1-me@harin.net
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: harinworks

sound/pci/ctxfi/ctatc.c

@@ -791,7 +791,8 @@ static int spdif_passthru_playback_get_resources(struct ct_atc *atc,
 	struct src *src;
 	int err;
 	int n_amixer = apcm->substream->runtime->channels, i;
-	unsigned int pitch, rsr = atc->pll_rate;
+	unsigned int pitch;
+	unsigned int rsr = atc->pll_rate ? atc->pll_rate : atc->rsr;
 
 	/* first release old resources */
 	atc_pcm_release_resources(atc, apcm);