audio: rate-limit "no bytes to copy" messages

When tearing down streams, when some of the pipelines have already
been deleted and some are still active, the remaining active
pipelines might experience no-data conditions. Currently this is
logged on every LL-scheduler period, i.e. every millisecond. This
isn't adding any useful information and in fact can create a flood
of outgoing IPC notifications, eventually blocking valid IPC replies
and leading to IPC timeouts. Rate-limit these logging entries to fix
the problem and relax the log.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

Author: lyakh

src/audio/host-zephyr.c

@@ -359,6 +359,9 @@ static void host_dma_cb(struct comp_dev *dev, size_t bytes)
 		host_common_one_shot(hd, bytes);
 }
 
+/* Minimum time between 2 consecutive "no bytes to copy" messages in milliseconds */
+#define SOF_MIN_NO_BYTES_INTERVAL_MS 20
+
 /**
  * Calculates bytes to be copied in normal mode.
  * @param dev Host component device.
@@ -403,9 +406,22 @@ static uint32_t host_get_copy_bytes_normal(struct host_data *hd, struct comp_dev
 	if (!(hd->ipc_host.feature_mask & BIT(IPC4_COPIER_FAST_MODE)))
 		dma_copy_bytes = MIN(hd->period_bytes, dma_copy_bytes);
 
-	if (!dma_copy_bytes)
-		comp_info(dev, "no bytes to copy, available samples: %d, free_samples: %d",
-			  avail_samples, free_samples);
+	if (!dma_copy_bytes) {
+		static uint64_t nobytes_last_logged;
+		static unsigned int n_skipped;
+		uint64_t now = k_uptime_get();
+		uint64_t delta = now - nobytes_last_logged;
+
+		if (delta > SOF_MIN_NO_BYTES_INTERVAL_MS) {
+			nobytes_last_logged = now;
+			comp_info(dev,
+				  "no bytes to copy, %u such events in last %llu ms, available samples: %d, free_samples: %d",
+				  n_skipped, delta, avail_samples, free_samples);
+			n_skipped = 0;
+		} else {
+			n_skipped++;
+		}
+	}
 
 	/* dma_copy_bytes should be aligned to minimum possible chunk of
 	 * data to be copied by dma.