Hello,
I'm trying to use the SoC TLV320AIC3x codec driver with sysclk 16384000 and ran into some problems with setting PLL; below is a patch against linux-2.6-asoc
note that the original code uses variables pll_r and pll_p instead of the loop variable r and p to compute tmp, this seems broken
further, the original code does not respect the constraints on j (>= 4, <= 55 for d==0) according to the codec's datasheet, and similarly for d!=0
I've tested the code with a number of reasonable sysclk values and got sane PLL values; please apply if acceptable
thanks, regards, p.
diff --git a/sound/soc/codecs/tlv320aic3x.c b/sound/soc/codecs/tlv320aic3x.c index 3395cf9..e84e473 100644 --- a/sound/soc/codecs/tlv320aic3x.c +++ b/sound/soc/codecs/tlv320aic3x.c @@ -766,9 +766,10 @@ static int aic3x_hw_params(struct snd_pcm_substream *substream, struct snd_soc_codec *codec = socdev->card->codec; struct aic3x_priv *aic3x = codec->private_data; int codec_clk = 0, bypass_pll = 0, fsref, last_clk = 0; - u8 data, r, p, pll_q, pll_p = 1, pll_r = 1, pll_j = 1; - u16 pll_d = 1; + u8 data, j, r, p, pll_q, pll_p = 1, pll_r = 1, pll_j = 1; + u16 d, pll_d = 1; u8 reg; + int clk;
/* select data word length */ data = @@ -835,47 +836,62 @@ static int aic3x_hw_params(struct snd_pcm_substream *substream, return 0;
/* Use PLL - * find an apropriate setup for j, d, r and p by iterating over - * p and r - j and d are calculated for each fraction. - * Up to 128 values are probed, the closest one wins the game. + * find an appropriate setup for j, d, r and p by iterating over + * p, r and j first, then trying to compute the fraction d. + * Up to 6528 values are probed, the closest one wins the game. * The sysclk is divided by 1000 to prevent integer overflows. */ codec_clk = (2048 * fsref) / (aic3x->sysclk / 1000);
- for (r = 1; r <= 16; r++) - for (p = 1; p <= 8; p++) { - int clk, tmp = (codec_clk * pll_r * 10) / pll_p; - u8 j = tmp / 10000; - u16 d = tmp % 10000; - - if (j > 63) - continue; - - if (d != 0 && aic3x->sysclk < 10000000) - continue; - - /* This is actually 1000 * ((j + (d/10000)) * r) / p - * The term had to be converted to get rid of the - * division by 10000 */ - clk = ((10000 * j * r) + (d * r)) / (10 * p); - - /* check whether this values get closer than the best - * ones we had before */ - if (abs(codec_clk - clk) < abs(codec_clk - last_clk)) { - pll_j = j; pll_d = d; pll_r = r; pll_p = p; - last_clk = clk; - } - - /* Early exit for exact matches */ - if (clk == codec_clk) - break; - } + for (r = 1; r <= 16; r++) + for (p = 1; p <= 8; p++) { + for (j = 4; j <= 55; j++) { + /* This is actually 1000 * ((j + (d/10000)) * r) / p + * The term had to be converted to get rid of the + * division by 10000; d = 0 here */ + int clk = (1000 * j * r) / p; + + /* check whether this values get closer than the best + * ones we had before */ + if (abs(codec_clk - clk) < abs(codec_clk - last_clk)) { + pll_j = j; pll_d = 0; pll_r = r; pll_p = p; + last_clk = clk; + } + + /* Early exit for exact matches */ + if (clk == codec_clk) + goto found; + } + } + + /* try with d != 0 */ + for (p = 1; p <= 8; p++) { + j = codec_clk * p / 1000; + + if (j < 4 || j > 11) continue; + + /* do not use codec_clk here since we'd loose precision */ + d = ((2048 * fsref * 10) / (aic3x->sysclk / 1000)) % 10000; + clk = (10000 * j + d) / (10 * p); + + /* check whether this values get closer than the best + * ones we had before */ + if (abs(codec_clk - clk) < abs(codec_clk - last_clk)) { + pll_j = j; pll_d = d; pll_r = 1; pll_p = 1; + last_clk = clk; + } + + /* Early exit for exact matches */ + if (clk == codec_clk) + goto found; + }
if (last_clk == 0) { printk(KERN_ERR "%s(): unable to setup PLL\n", __func__); return -EINVAL; }
+found: data = aic3x_read_reg_cache(codec, AIC3X_PLL_PROGA_REG); aic3x_write(codec, AIC3X_PLL_PROGA_REG, data | (pll_p << PLLP_SHIFT)); aic3x_write(codec, AIC3X_OVRF_STATUS_AND_PLLR_REG, pll_r << PLLR_SHIFT);