From 0e3a71c3749fa451505a67a61d61e142a96ceb23 Mon Sep 17 00:00:00 2001 From: Antti Palosaari Date: Tue, 21 Apr 2015 21:18:45 -0300 Subject: [media] e4000: revise synthesizer calculation Update synthesizer calculation to model I prefer nowadays. It is mostly just renaming some variables to ones I think are most standard. Also add 'schematic' of synthesizer following my current understanding. Signed-off-by: Antti Palosaari Signed-off-by: Mauro Carvalho Chehab --- drivers/media/tuners/e4000.c | 44 +++++++++++++++++++++++++++------------ drivers/media/tuners/e4000_priv.h | 4 ++-- 2 files changed, 33 insertions(+), 15 deletions(-) (limited to 'drivers/media/tuners') diff --git a/drivers/media/tuners/e4000.c b/drivers/media/tuners/e4000.c index 510239f80c0d..cda8bcf164de 100644 --- a/drivers/media/tuners/e4000.c +++ b/drivers/media/tuners/e4000.c @@ -115,8 +115,8 @@ static int e4000_set_params(struct dvb_frontend *fe) { struct e4000 *s = fe->tuner_priv; struct dtv_frontend_properties *c = &fe->dtv_property_cache; - int ret, i, sigma_delta; - unsigned int pll_n, pll_f; + int ret, i; + unsigned int div_n, k, k_cw, div_out; u64 f_vco; u8 buf[5], i_data[4], q_data[4]; @@ -129,7 +129,21 @@ static int e4000_set_params(struct dvb_frontend *fe) if (ret) goto err; - /* PLL */ + /* + * Fractional-N synthesizer + * + * +----------------------------+ + * v | + * Fref +----+ +-------+ +------+ +---+ + * ------> | PD | --> | VCO | ------> | /N.F | <-- | K | + * +----+ +-------+ +------+ +---+ + * | + * | + * v + * +-------+ Fout + * | /Rout | ------> + * +-------+ + */ for (i = 0; i < ARRAY_SIZE(e4000_pll_lut); i++) { if (c->frequency <= e4000_pll_lut[i].freq) break; @@ -140,18 +154,22 @@ static int e4000_set_params(struct dvb_frontend *fe) goto err; } - f_vco = 1ull * c->frequency * e4000_pll_lut[i].mul; - pll_n = div_u64_rem(f_vco, s->clock, &pll_f); - sigma_delta = div_u64(0x10000ULL * pll_f, s->clock); - buf[0] = pll_n; - buf[1] = (sigma_delta >> 0) & 0xff; - buf[2] = (sigma_delta >> 8) & 0xff; - buf[3] = 0x00; - buf[4] = e4000_pll_lut[i].div; + #define F_REF s->clock + div_out = e4000_pll_lut[i].div_out; + f_vco = (u64) c->frequency * div_out; + /* calculate PLL integer and fractional control word */ + div_n = div_u64_rem(f_vco, F_REF, &k); + k_cw = div_u64((u64) k * 0x10000, F_REF); - dev_dbg(&s->client->dev, "f_vco=%llu pll div=%d sigma_delta=%04x\n", - f_vco, buf[0], sigma_delta); + dev_dbg(&s->client->dev, + "frequency=%u f_vco=%llu F_REF=%u div_n=%u k=%u k_cw=%04x div_out=%u\n", + c->frequency, f_vco, F_REF, div_n, k, k_cw, div_out); + buf[0] = div_n; + buf[1] = (k_cw >> 0) & 0xff; + buf[2] = (k_cw >> 8) & 0xff; + buf[3] = 0x00; + buf[4] = e4000_pll_lut[i].div_out_reg; ret = regmap_bulk_write(s->regmap, 0x09, buf, 5); if (ret) goto err; diff --git a/drivers/media/tuners/e4000_priv.h b/drivers/media/tuners/e4000_priv.h index cb0070483e65..6214fc05bf70 100644 --- a/drivers/media/tuners/e4000_priv.h +++ b/drivers/media/tuners/e4000_priv.h @@ -49,8 +49,8 @@ struct e4000 { struct e4000_pll { u32 freq; - u8 div; - u8 mul; + u8 div_out_reg; + u8 div_out; }; static const struct e4000_pll e4000_pll_lut[] = { -- cgit v1.2.3-59-g8ed1b