From 75564e3a5016651f1c7f8eec63b557e24d6d1e17 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Fri, 4 Oct 2019 08:42:47 -0300 Subject: [PATCH] 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: Mauro Carvalho Chehab Signed-off-by: Sean Young --- drivers/media/dvb-frontends/mb86a20s.c | 54 +++++++++++--------------- 1 file changed, 23 insertions(+), 31 deletions(-) diff --git a/drivers/media/dvb-frontends/mb86a20s.c b/drivers/media/dvb-frontends/mb86a20s.c index 4e50441c247a..a7faf0cf8788 100644 --- a/drivers/media/dvb-frontends/mb86a20s.c +++ b/drivers/media/dvb-frontends/mb86a20s.c @@ -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); -- 2.45.2