Peter Meerwald wrote:
Hello Vladimir,
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
I've made the simple test application to calculate pll_p/r/j/d values using current tlv320aic3x clock calculation scheme and I've got: samplerate=8000: pll_p=1, pll_r=1, pll_j=6, pll_d=0, hence FSREF=(sysclk * [pll_j].[pll_d] * pll_r) / (2048 * pll_p) = 48000 samplerate=11025: pll_p=1, pll_r=1, pll_j=5, pll_d=5120, hence FSREF= 44096 samplerate=16000: pll_p=1, pll_r=1, pll_j=6, pll_d=0, hence FSREF=48000 samplerate=22050: pll_p=1, pll_r=1, pll_j=5, pll_d=5120, hence FSREF= 44096 samplerate=32000: pll_p=1, pll_r=1, pll_j=6, pll_d=0, hence FSREF=48000 samplerate=44100: pll_p=1, pll_r=1, pll_j=5, pll_d=5120, hence FSREF= 44096 samplerate=48000: pll_p=1, pll_r=1, pll_j=6, pll_d=0, hence FSREF=48000 samplerate=64000: pll_p=1, pll_r=1, pll_j=6, pll_d=0, hence FSREF=48000, note that here we used DUAL_RATE_MODE, hence FSREF=96000 samplerate=88200: pll_p=1, pll_r=1, pll_j=5, pll_d=5120, hence FSREF= 44096, note that here we used DUAL_RATE_MODE hence FSREF=88192 samplerate=96000: pll_p=1, pll_r=1, pll_j=6, pll_d=0, hence FSREF=48000, note that here we used DUAL_RATE_MODE hence FSREF = 96000
Hence according to current code the calculations of desired FSREF is correct for sysclk=16384000 I've not tried it with your patch since I don't actually understand what do you fix? :)
- loop variables are r and p but for computation of j the variables
pll_r and pll_p are used; I think r and p should be used in the computation of j, your code below:
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;further, the codec datasheet mandates certain ranges for 'good performance', 4 <= j <= 55 (for d==0) and 4 <= j <= 11 (for d!=0) which are not checked for
Correct.
- d should actually be 5125 and not 5120
Now I see, I've verified your code handles this. This actually produce more accuracy for FSREF.
I just tested your patch works fine with sysclk=16384000 and 12288000 but fails with 11286900: it returns FSREF=45467 instead of desired 44100. I think that this is a valuable difference. Please check it.
Regards, Vladimir
- appropriate is spell appropriately :)
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 thebest
* 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);