[media] mceusb: buffer parsing fixups for 1st-gen device

If we pass in an offset, we shouldn't skip 2 bytes. And the first-gen
hardware generates a constant stream of interrupts, always with two
header bytes, and if there's been no IR, with nothing else. Bail from
ir processing without calling ir_handle_raw_event when we get such a
buffer delivered to us.

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/IR/mceusb.c

@@ -446,7 +446,7 @@ static void mceusb_dev_printdata(struct mceusb_dev *ir, char *buf,
 		return;
 
 	/* skip meaningless 0xb1 0x60 header bytes on orig receiver */
-	if (ir->flags.microsoft_gen1 && !out)
+	if (ir->flags.microsoft_gen1 && !out && !offset)
 		skip = 2;
 
 	if (len <= skip)
@@ -807,6 +807,10 @@ static void mceusb_process_ir_data(struct mceusb_dev *ir, int buf_len)
 	if (ir->flags.microsoft_gen1)
 		i = 2;
 
+	/* if there's no data, just return now */
+	if (buf_len <= i)
+		return;
+
 	for (; i < buf_len; i++) {
 		switch (ir->parser_state) {
 		case SUBCMD: