[media] tda10023: Don't use a magic numbers for QAM modulation

Convert the existing data struct to use the QAM modulation macros,
instead of assuming that they're numbered from 0 to 5.

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

drivers/media/dvb/frontends/tda10023.c

@@ -298,42 +298,62 @@ static int tda10023_init (struct dvb_frontend *fe)
 	return 0;
 }
 
+struct qam_params {
+	u8 qam, lockthr, mseth, aref, agcrefnyq, eragnyq_thd;
+};
+
 static int tda10023_set_parameters (struct dvb_frontend *fe,
 			    struct dvb_frontend_parameters *p)
 {
 	struct tda10023_state* state = fe->demodulator_priv;
-
-	static int qamvals[6][6] = {
-		//  QAM   LOCKTHR  MSETH   AREF AGCREFNYQ  ERAGCNYQ_THD
-		{ (5<<2),  0x78,    0x8c,   0x96,   0x78,   0x4c  },  // 4 QAM
-		{ (0<<2),  0x87,    0xa2,   0x91,   0x8c,   0x57  },  // 16 QAM
-		{ (1<<2),  0x64,    0x74,   0x96,   0x8c,   0x57  },  // 32 QAM
-		{ (2<<2),  0x46,    0x43,   0x6a,   0x6a,   0x44  },  // 64 QAM
-		{ (3<<2),  0x36,    0x34,   0x7e,   0x78,   0x4c  },  // 128 QAM
-		{ (4<<2),  0x26,    0x23,   0x6c,   0x5c,   0x3c  },  // 256 QAM
+	static const struct qam_params qam_params[] = {
+		/* Modulation  QAM    LOCKTHR   MSETH   AREF AGCREFNYQ ERAGCNYQ_THD */
+		[QPSK]    = { (5<<2),  0x78,    0x8c,   0x96,   0x78,   0x4c  },
+		[QAM_16]  = { (0<<2),  0x87,    0xa2,   0x91,   0x8c,   0x57  },
+		[QAM_32]  = { (1<<2),  0x64,    0x74,   0x96,   0x8c,   0x57  },
+		[QAM_64]  = { (2<<2),  0x46,    0x43,   0x6a,   0x6a,   0x44  },
+		[QAM_128] = { (3<<2),  0x36,    0x34,   0x7e,   0x78,   0x4c  },
+		[QAM_256] = { (4<<2),  0x26,    0x23,   0x6c,   0x5c,   0x3c  },
 	};
-
-	int qam = p->u.qam.modulation;
-
-	if (qam < 0 || qam > 5)
+	unsigned qam = p->u.qam.modulation;
+
+	/*
+	 * gcc optimizes the code bellow the same way as it would code:
+	 *		 "if (qam > 5) return -EINVAL;"
+	 * Yet, the code is clearer, as it shows what QAM standards are
+	 * supported by the driver, and avoids the usage of magic numbers on
+	 * it.
+	 */
+	switch (qam) {
+	case QPSK:
+	case QAM_16:
+	case QAM_32:
+	case QAM_64:
+	case QAM_128:
+	case QAM_256:
+		break;
+	default:
 		return -EINVAL;
+	}
 
 	if (fe->ops.tuner_ops.set_params) {
 		fe->ops.tuner_ops.set_params(fe, p);
 		if (fe->ops.i2c_gate_ctrl) fe->ops.i2c_gate_ctrl(fe, 0);
 	}
 
 	tda10023_set_symbolrate (state, p->u.qam.symbol_rate);
-	tda10023_writereg (state, 0x05, qamvals[qam][1]);
-	tda10023_writereg (state, 0x08, qamvals[qam][2]);
-	tda10023_writereg (state, 0x09, qamvals[qam][3]);
-	tda10023_writereg (state, 0xb4, qamvals[qam][4]);
-	tda10023_writereg (state, 0xb6, qamvals[qam][5]);
-
-//	tda10023_writereg (state, 0x04, (p->inversion?0x12:0x32));
-//	tda10023_writebit (state, 0x04, 0x60, (p->inversion?0:0x20));
-	tda10023_writebit (state, 0x04, 0x40, 0x40);
-	tda10023_setup_reg0 (state, qamvals[qam][0]);
+	tda10023_writereg(state, 0x05, qam_params[qam].lockthr);
+	tda10023_writereg(state, 0x08, qam_params[qam].mseth);
+	tda10023_writereg(state, 0x09, qam_params[qam].aref);
+	tda10023_writereg(state, 0xb4, qam_params[qam].agcrefnyq);
+	tda10023_writereg(state, 0xb6, qam_params[qam].eragnyq_thd);
+
+#if 0
+	tda10023_writereg(state, 0x04, (p->inversion ? 0x12 : 0x32));
+	tda10023_writebit(state, 0x04, 0x60, (p->inversion ? 0 : 0x20));
+#endif
+	tda10023_writebit(state, 0x04, 0x40, 0x40);
+	tda10023_setup_reg0(state, qam_params[qam].qam);
 
 	return 0;
 }