ALSA: snd-usb-caiaq: drop bogus iso packets

Drop inbound packets that are smaller than expected. This has been
observed at the very beginning of the streaming transaction.

And when the hardware is in panic mode (which can only very rarely
happen in case of massive EMI chaos), mute the input channels.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Tested-by: Mark Hills <mark@pogo.org.uk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/caiaq/caiaq-audio.c b/sound/usb/caiaq/caiaq-audio.c
index 577b112..08d51e0 100644
--- a/sound/usb/caiaq/caiaq-audio.c
+++ b/sound/usb/caiaq/caiaq-audio.c
@@ -377,6 +377,9 @@
 
 		for (stream = 0; stream < dev->n_streams; stream++, i++) {
 			sub = dev->sub_capture[stream];
+			if (dev->input_panic)
+				usb_buf[i] = 0;
+
 			if (sub) {
 				struct snd_pcm_runtime *rt = sub->runtime;
 				char *audio_buf = rt->dma_area;
@@ -398,6 +401,9 @@
 	if (!dev->streaming)
 		return;
 
+	if (iso->actual_length < dev->bpp)
+		return;
+
 	switch (dev->spec.data_alignment) {
 	case 0:
 		read_in_urb_mode0(dev, urb, iso);