[PATCH 3/3] ASoC: qcom: q6asm-dai: wrap the position of a full ring to 0

[Vladyslav Tymoshchuk <tvlad744@gmail.com>]

Commit 44432315444c ("ASoC: qcom: q6asm-dai: use q6asm_get_hw_pointer")
took the position from the number of period buffers the DSP has
returned in the current lap, 1..periods, and reports one frame less
than that, as q6apm-dai does.

One frame short, a playback stream whose application stops feeding it
never reaches the stop threshold: the DSP returns the last queued
buffer, the position stops at appl_ptr - 1 and no period interrupt
comes any more, so ALSA never detects the underrun, the stream stays
RUNNING and drain only ends on its timeout. On capture, the last frame
of each period is held back until the next one.

Before that commit the position wrapped to 0 at the end of the ring.
Do that again, as for q6apm-dai.

Fixes: 44432315444c ("ASoC: qcom: q6asm-dai: use q6asm_get_hw_pointer")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Vladyslav Tymoshchuk <tvlad744@gmail.com>
---
Compile-tested only: I have no Q6ASM hardware (sdm845, sm8250 RB5...).
A test on such a board would be welcome. The hw pointer of q6asm is not
reset on a new prepare either (the same as patch 2 for q6apm); I left
that alone as I cannot test the q6asm prepare paths.

 sound/soc/qcom/qdsp6/q6asm-dai.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/sound/soc/qcom/qdsp6/q6asm-dai.c b/sound/soc/qcom/qdsp6/q6asm-dai.c
index cd4f82bb8cc7..4261c3048c36 100644
--- a/sound/soc/qcom/qdsp6/q6asm-dai.c
+++ b/sound/soc/qcom/qdsp6/q6asm-dai.c
@@ -485,11 +485,10 @@ static snd_pcm_uframes_t q6asm_dai_pointer(struct snd_soc_component *component,
 	struct q6asm_dai_rtd *prtd = runtime->private_data;
 	snd_pcm_uframes_t ptr;
 
-	ptr = q6asm_get_hw_pointer(prtd->audio_client, substream->stream) * runtime->period_size;
-	if (ptr)
-		return ptr - 1;
+	/* a full lap of period buffers is the start of the ring again */
+	ptr = q6asm_get_hw_pointer(prtd->audio_client, substream->stream) % runtime->periods;
 
-	return 0;
+	return ptr * runtime->period_size;
 }
 
 static int q6asm_dai_hw_params(struct snd_soc_component *component,
-- 
2.43.0