ASoC: SOF: ipc4-pcm: do not report invalid samples

If the application has been late in supplying samples, the streams
can be in underrun conditions. This is an error condition, but the delay
logic should not report abnormal values in this case. Add a sanity
check to the delay calculation and if the value is clearly out-of-bounds,
return 0 delay and emit a ratelimited warning to kernel log.

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

Author: kv2019i

sound/soc/sof/ipc4-pcm.c

@@ -1279,6 +1279,13 @@ 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,
+				    "delay reporting inaccurate due to xrun, host %llu dai_cnt %llu",
+				    host_cnt, dai_cnt);
+		time_info->delay = 0;
+	}
+
 	/* convert delay to host time */
 	time_info->delay = sof_ipc4_time_dai_to_host(time_info, time_info->delay);