Commit 75564e3a authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
Browse files

media: mb86a20s: make the bit rate estimation function more generic 



While 99% of the implementation of the bitrate estimation
routine for ISDB-T is generic, the current approach mangles it
with some mb86a20s-specific thing.

Split the calculus from the specific stuff, in order to make
easier to use the same approach on other drivers requiring
a similar formula.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarSean Young <sean@mess.org>
parent ca8f245f

drivers/media/dvb-frontends/mb86a20s.c

+23 −31
Original line number Diff line number Diff line
@@ -517,7 +517,7 @@ static void mb86a20s_reset_frontend_cache(struct dvb_frontend *fe) 
 * Estimates the bit rate using the per-segment bit rate given by

 * ABNT/NBR 15601 spec (table 4).

 */

static u32 isdbt_rate[3][5][4] = {

static const u32 isdbt_rate[3][5][4] = {

	{	/* DQPSK/QPSK */

		{  280850,  312060,  330420,  340430 },	/* 1/2 */

		{  374470,  416080,  440560,  453910 },	/* 2/3 */
@@ -539,13 +539,9 @@ static u32 isdbt_rate[3][5][4] = { 
	}

};



static void mb86a20s_layer_bitrate(struct dvb_frontend *fe, u32 layer,

				   u32 modulation, u32 forward_error_correction,

				   u32 guard_interval,

				   u32 segment)

static u32 isdbt_layer_min_bitrate(struct dtv_frontend_properties *c,

				   u32 layer)

{

	struct mb86a20s_state *state = fe->demodulator_priv;

	u32 rate;

	int mod, fec, guard;



	/*
@@ -553,7 +549,7 @@ static void mb86a20s_layer_bitrate(struct dvb_frontend *fe, u32 layer, 
	 * to consider the lowest bit rate, to avoid taking too long time

	 * to get BER.

	 */

	switch (modulation) {

	switch (c->layer[layer].modulation) {

	case DQPSK:

	case QPSK:

	default:
@@ -567,7 +563,7 @@ static void mb86a20s_layer_bitrate(struct dvb_frontend *fe, u32 layer, 
		break;

	}



	switch (forward_error_correction) {

	switch (c->layer[layer].fec) {

	default:

	case FEC_1_2:

	case FEC_AUTO:
@@ -587,7 +583,7 @@ static void mb86a20s_layer_bitrate(struct dvb_frontend *fe, u32 layer, 
		break;

	}



	switch (guard_interval) {

	switch (c->guard_interval) {

	default:

	case GUARD_INTERVAL_1_4:

		guard = 0;
@@ -603,29 +599,14 @@ static void mb86a20s_layer_bitrate(struct dvb_frontend *fe, u32 layer, 
		break;

	}



	/* Samples BER at BER_SAMPLING_RATE seconds */

	rate = isdbt_rate[mod][fec][guard] * segment * BER_SAMPLING_RATE;



	/* Avoids sampling too quickly or to overflow the register */

	if (rate < 256)

		rate = 256;

	else if (rate > (1 << 24) - 1)

		rate = (1 << 24) - 1;



	dev_dbg(&state->i2c->dev,

		"%s: layer %c bitrate: %d kbps; counter = %d (0x%06x)\n",

		__func__, 'A' + layer,

		segment * isdbt_rate[mod][fec][guard]/1000,

		rate, rate);



	state->estimated_rate[layer] = rate;

	return isdbt_rate[mod][fec][guard] * c->layer[layer].segment_count;

}



static int mb86a20s_get_frontend(struct dvb_frontend *fe)

{

	struct mb86a20s_state *state = fe->demodulator_priv;

	struct dtv_frontend_properties *c = &fe->dtv_property_cache;

	int layer, rc;

	int layer, rc, rate, counter;



	dev_dbg(&state->i2c->dev, "%s called.\n", __func__);
@@ -676,10 +657,21 @@ static int mb86a20s_get_frontend(struct dvb_frontend *fe) 
		dev_dbg(&state->i2c->dev, "%s: interleaving %d.\n",

			__func__, rc);

		c->layer[layer].interleaving = rc;

		mb86a20s_layer_bitrate(fe, layer, c->layer[layer].modulation,

				       c->layer[layer].fec,

				       c->guard_interval,

				       c->layer[layer].segment_count);



		rate = isdbt_layer_min_bitrate(c, layer);

		counter = rate * BER_SAMPLING_RATE;



		/* Avoids sampling too quickly or to overflow the register */

		if (counter < 256)

			counter = 256;

		else if (counter > (1 << 24) - 1)

			counter = (1 << 24) - 1;



		dev_dbg(&state->i2c->dev,

			"%s: layer %c bitrate: %d kbps; counter = %d (0x%06x)\n",

			__func__, 'A' + layer, rate / 1000, counter, counter);



		state->estimated_rate[layer] = counter;

	}



	rc = mb86a20s_writereg(state, 0x6d, 0x84);