ALSA: snd-usb-caiaq: only warn once on streaming errors

Limit the number of printed warnings to one in case of streaming errors.
printk() happens to be expensive, especially in code called as often as
here.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/caiaq/caiaq-audio.c

@@ -114,6 +114,7 @@ static int stream_start(struct snd_usb_caiaqdev *dev)
 	dev->output_panic = 0;
 	dev->first_packet = 1;
 	dev->streaming = 1;
+	dev->warned = 0;
 
 	for (i = 0; i < N_URBS; i++) {
 		ret = usb_submit_urb(dev->data_urbs_in[i], GFP_ATOMIC);
@@ -406,10 +407,11 @@ static void read_in_urb(struct snd_usb_caiaqdev *dev,
 		break;
 	}
 
-	if (dev->input_panic || dev->output_panic) {
+	if ((dev->input_panic || dev->output_panic) && !dev->warned) {
 		debug("streaming error detected %s %s\n", 
 				dev->input_panic ? "(input)" : "",
 				dev->output_panic ? "(output)" : "");
+		dev->warned = 1;
 	}
 }
 

sound/usb/caiaq/caiaq-device.h

@@ -89,7 +89,7 @@ struct snd_usb_caiaqdev {
 	int audio_out_buf_pos[MAX_STREAMS];
 	int period_in_count[MAX_STREAMS];
 	int period_out_count[MAX_STREAMS];
-	int input_panic, output_panic;
+	int input_panic, output_panic, warned;
 	char *audio_in_buf, *audio_out_buf;
 	unsigned int samplerates;