ASoC: SOF: ipc4-pcm: do not report invalid delay values

If the stream hits an xrun condition, the delay calculation results
in invalid, very large values. The application has no way to interpret
these values as it doesn't know the internal boundary limits used
in delay calculation. Add a sanity to check the delay value before
it is reported back. If it's clearly invalid, return a zero delay and
emit a rate limited warning to kernel log.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

sound/soc/sof/ipc4-pcm.c

@@ -1261,6 +1261,12 @@ static int sof_ipc4_pcm_pointer(struct snd_soc_component *component,
 	else
 		time_info->delay = head_cnt - tail_cnt;
 
+	if (time_info->delay > (DELAY_BOUNDARY >> 1)) {
+		dev_dbg_ratelimited(sdev->dev, "inaccurate delay, host %llu dai_cnt %llu",
+				    host_cnt, dai_cnt);
+		time_info->delay = 0;
+	}
+
 	/*
 	 * Convert the host byte counter to PCM pointer which wraps in buffer
 	 * and it is in frames