diff --git a/src/tuner_r82xx.c b/src/tuner_r82xx.c index 38d4802..a6d28d2 100644 --- a/src/tuner_r82xx.c +++ b/src/tuner_r82xx.c @@ -429,12 +429,11 @@ static int r82xx_set_pll(struct r82xx_priv *priv, uint32_t freq) int rc, i; unsigned sleep_time = 10000; uint64_t vco_freq; - uint32_t vco_fra; /* VCO contribution by SDM (kHz) */ - uint32_t vco_min = 1770000; - uint32_t vco_max = vco_min * 2; - uint32_t freq_khz, pll_ref, pll_ref_khz; - uint16_t n_sdm = 2; - uint16_t sdm = 0; + uint64_t vco_div; + uint32_t vco_min = 1770000; /* kHz */ + uint32_t vco_max = vco_min * 2; /* kHz */ + uint32_t freq_khz, pll_ref; + uint32_t sdm = 0; uint8_t mix_div = 2; uint8_t div_buf = 0; uint8_t div_num = 0; @@ -446,7 +445,6 @@ static int r82xx_set_pll(struct r82xx_priv *priv, uint32_t freq) /* Frequency in kHz */ freq_khz = (freq + 500) / 1000; pll_ref = priv->cfg->xtal; - pll_ref_khz = (priv->cfg->xtal + 500) / 1000; rc = r82xx_write_reg_mask(priv, 0x10, refdiv2, 0x10); if (rc < 0) @@ -495,8 +493,24 @@ static int r82xx_set_pll(struct r82xx_priv *priv, uint32_t freq) return rc; vco_freq = (uint64_t)freq * (uint64_t)mix_div; - nint = vco_freq / (2 * pll_ref); - vco_fra = (vco_freq - 2 * pll_ref * nint) / 1000; + + /* We want to approximate: + * vco_freq / (2 * pll_ref) + * + * in the form: + * nint + sdm/65536 + * + * where nint,sdm are integers and 0 < nint, 0 <= sdm < 65536 + * + * Scaling to fixed point and rounding: + * + * vco_div = 65536*(nint + sdm/65536) = int( 0.5 + 65536 * vco_freq / (2 * pll_ref) ) + * vco_div = 65536*nint + sdm = int( (pll_ref + 65536 * vco_freq) / (2 * pll_ref) ) + */ + + vco_div = (pll_ref + 65536 * vco_freq) / (2 * pll_ref); + nint = (uint32_t) (vco_div / 65536); + sdm = (uint32_t) (vco_div % 65536); if (nint > ((128 / vco_power_ref) - 1)) { fprintf(stderr, "[R82XX] No valid PLL values for %u Hz!\n", freq); @@ -511,7 +525,7 @@ static int r82xx_set_pll(struct r82xx_priv *priv, uint32_t freq) return rc; /* pw_sdm */ - if (!vco_fra) + if (sdm == 0) val = 0x08; else val = 0x00; @@ -520,17 +534,6 @@ static int r82xx_set_pll(struct r82xx_priv *priv, uint32_t freq) if (rc < 0) return rc; - /* sdm calculator */ - while (vco_fra > 1) { - if (vco_fra > (2 * pll_ref_khz / n_sdm)) { - sdm = sdm + 32768 / (n_sdm / 2); - vco_fra = vco_fra - 2 * pll_ref_khz / n_sdm; - if (n_sdm >= 0x8000) - break; - } - n_sdm <<= 1; - } - rc = r82xx_write_reg(priv, 0x16, sdm >> 8); if (rc < 0) return rc;