[PATCH] dvb: frontend: mt352: fix signal strength reading

Fix two problems with the signal strength value in the mt352.c frontend:
1. the 4 most significant bits are zeroed - shift and mask wrong way round
2. need to align the 12 bits from the registers at the top of the 16 bit
   returned value - otherwise the range is not 0 to 0xffff its 0xf000 to 0xffff
Signed-off-by: NBarry Scott <barry.scott@onelan.co.uk>
Signed-off-by: NJohannes Stezenbach <js@linuxtv.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/media/dvb/frontends/mt352.c

@@ -462,9 +462,11 @@ static int mt352_read_signal_strength(struct dvb_frontend* fe, u16* strength)
 {
 	struct mt352_state* state = fe->demodulator_priv;
 
-	u16 signal = ((mt352_read_register(state, AGC_GAIN_1) << 8) & 0x0f) |
-		      (mt352_read_register(state, AGC_GAIN_0));
+	/* align the 12 bit AGC gain with the most significant bits */
+	u16 signal = ((mt352_read_register(state, AGC_GAIN_1) & 0x0f) << 12) |
+		(mt352_read_register(state, AGC_GAIN_0) << 4);
 
+	/* inverse of gain is signal strength */
 	*strength = ~signal;
 	return 0;
 }