[media] media: rc: ir-sharp-decoder: add support for Denon variant of the protocol

Denon also uses the Sharp protocol, however with different check bits.

It would have been also possible to add this as a separate protocol
but this may not be worth the effort.

Successfully tested with a Denon RC-1002 remote control.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/rc/Kconfig

@@ -101,7 +101,8 @@ config IR_SHARP_DECODER
 
 	---help---
 	   Enable this option if you have an infrared remote control which
-	   uses the Sharp protocol, and you need software decoding support.
+	   uses the Sharp protocol (Sharp, Denon), and you need software
+	   decoding support.
 
 config IR_MCE_KBD_DECODER
 	tristate "Enable IR raw decoder for the MCE keyboard/mouse protocol"

drivers/media/rc/ir-sharp-decoder.c

@@ -118,7 +118,9 @@ static int ir_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev)
 
 		if (data->count == SHARP_NBITS) {
 			/* exp,chk bits should be 1,0 */
-			if ((data->bits & 0x3) != 0x2)
+			if ((data->bits & 0x3) != 0x2 &&
+			/* DENON variant, both chk bits 0 */
+			    (data->bits & 0x3) != 0x0)
 				break;
 			data->state = STATE_ECHO_SPACE;
 		} else {