[PATCH] STV0288 Fast Channel Acquisition

[Malcolm Priestley <tvboxspy@gmail.com>]

On Wed, 2011-06-29 at 15:16 +0200, Sébastien RAILLARD (COEXSI) wrote:

> On some other transponders, like ASTRA 19.2E 11567-V-22000, the card nearly
> never manage to get the lock: it's looking like the signal isn't good
> enough.
> I turned on the debugging of the stb6000 and stv0288 modules, but I can't
> see anything wrong.

I have had similar problems with the stv0288 on astra 19.2 and 28.2 with
various frequencies.

I have been using this patch for some time which seems to improve
things.

The STV0288 has a fast channel function which eliminates
the need for software carrier search.

The patch removes the slow carrier search and replaces
it with this faster and more reliable built-in chip function.

If carrier is lost while channel is running, fast channel
attempts to recover it.

The patch also reguires registers 50-57 to be set correctly
with inittab. All current combinations in the kernel media
tree have been checked and tested.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
---
 drivers/media/dvb/frontends/stv0288.c |   75 +++++++++++++++++++++-----------
 1 files changed, 49 insertions(+), 26 deletions(-)

diff --git a/drivers/media/dvb/frontends/stv0288.c b/drivers/media/dvb/frontends/stv0288.c
index 8e0cfad..fa5cba5 100644
--- a/drivers/media/dvb/frontends/stv0288.c
+++ b/drivers/media/dvb/frontends/stv0288.c
@@ -142,6 +142,12 @@ static int stv0288_set_symbolrate(struct dvb_frontend *fe, u32 srate)
 		stv0288_writeregI(state, 0x28, b[0]);
 		stv0288_writeregI(state, 0x29, b[1]);
 		stv0288_writeregI(state, 0x2a, b[2]);
+
+		stv0288_writeregI(state, 0x22, 0x0);
+		stv0288_writeregI(state, 0x23, 0x0);
+		stv0288_writeregI(state, 0x2b, 0x0);
+		stv0288_writeregI(state, 0x2c, 0x0);
+
 		dprintk("stv0288: stv0288_set_symbolrate\n");
 
 	return 0;
@@ -309,12 +315,13 @@ static u8 stv0288_inittab[] = {
 	0xf1, 0x0,
 	0xf2, 0xc0,
 	0x51, 0x36,
-	0x52, 0x09,
-	0x53, 0x94,
-	0x54, 0x62,
-	0x55, 0x29,
-	0x56, 0x64,
-	0x57, 0x2b,
+	0x52, 0x21,
+	/* Fast Channel MIN/MAX Freqency Bounds MSB bit 7 sets stop */
+	0x53, 0x94, /*Min MSB (0-6)*/
+	0x54, 0x62, /*Min LSB*/
+	0x55, 0x29, /*Max MSB (0-6)*/
+	0x56, 0x64, /*Max LSB*/
+	0x57, 0x2b, /* Increment (signed) */
 	0xff, 0xff,
 };
 
@@ -356,6 +363,35 @@ static int stv0288_init(struct dvb_frontend *fe)
 	return 0;
 }
 
+/* STV0288 Fast channel accquisition and blind search */
+static int stv0288_get_fast(struct dvb_frontend *fe)
+{
+	struct stv0288_state *state = fe->demodulator_priv;
+	int timeout = 0;
+
+	/* Coarse Tune */
+	stv0288_writeregI(state, 0x50, 0x35);
+	/* Wait 15ms */
+	msleep(15);
+	/* Fine Tune Control & Center Carrier */
+	stv0288_writeregI(state, 0x50, 0x16);
+	/* Check for Timing lock */
+	while (!(stv0288_readreg(state, 0x1e) & 0x80)) {
+		if (timeout++ > 5)
+			return -EINVAL;
+		msleep(15);
+	}
+
+	/* Center Carrier for further length of time */
+	stv0288_writeregI(state, 0x50, 0x14);
+	udelay(500);
+	/* Fast Search End*/
+	stv0288_writeregI(state, 0x50, 0x10);
+
+	return 0;
+}
+
+
 static int stv0288_read_status(struct dvb_frontend *fe, fe_status_t *status)
 {
 	struct stv0288_state *state = fe->demodulator_priv;
@@ -369,6 +405,9 @@ static int stv0288_read_status(struct dvb_frontend *fe, fe_status_t *status)
 	*status = 0;
 	if (sync & 0x80)
 		*status |= FE_HAS_CARRIER | FE_HAS_SIGNAL;
+		else
+		stv0288_get_fast(fe); /*try to recover*/
+
 	if (sync & 0x10)
 		*status |= FE_HAS_VITERBI;
 	if (sync & 0x08) {
@@ -458,9 +497,7 @@ static int stv0288_set_frontend(struct dvb_frontend *fe,
 {
 	struct stv0288_state *state = fe->demodulator_priv;
 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
-
-	char tm;
-	unsigned char tda[3];
+	int ret = 0;
 
 	dprintk("%s : FE_SET_FRONTEND\n", __func__);
 
@@ -487,28 +524,14 @@ static int stv0288_set_frontend(struct dvb_frontend *fe,
 	stv0288_set_symbolrate(fe, c->symbol_rate);
 	/* Carrier lock control register */
 	stv0288_writeregI(state, 0x15, 0xc5);
-
-	tda[0] = 0x2b; /* CFRM */
-	tda[2] = 0x0; /* CFRL */
-	for (tm = -6; tm < 7;) {
-		/* Viterbi status */
-		if (stv0288_readreg(state, 0x24) & 0x8)
-			break;
-
-		tda[2] += 40;
-		if (tda[2] < 40)
-			tm++;
-		tda[1] = (unsigned char)tm;
-		stv0288_writeregI(state, 0x2b, tda[1]);
-		stv0288_writeregI(state, 0x2c, tda[2]);
-		udelay(30);
-	}
+	/* Search for carrier */
+	ret = stv0288_get_fast(fe);
 
 	state->tuner_frequency = c->frequency;
 	state->fec_inner = FEC_AUTO;
 	state->symbol_rate = c->symbol_rate;
 
-	return 0;
+	return ret;
 }
 
 static int stv0288_i2c_gate_ctrl(struct dvb_frontend *fe, int enable)
-- 
1.7.4.1