ASoC: arizona: fref must be limited in pseudo-fractional mode
When the FLL is in pseudo-fractional mode there is an additional
limit on fref based on the fratio, to prevent aliasing around the
Nyquist frequency. If fref exceeds this limit the refclk divider
must be increased and the calculation tried again until a suitable
combination of fref and fratio is found or we have to fall back to
integer mode.
This patch also adds some debug log prints around this code.
Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/codecs/arizona.c b/sound/soc/codecs/arizona.c
index 33143fe..9178531 100644
--- a/sound/soc/codecs/arizona.c
+++ b/sound/soc/codecs/arizona.c
@@ -1929,6 +1929,25 @@
{ 1000000, 13500000, 0, 1 },
};
+static const unsigned int pseudo_fref_max[ARIZONA_FLL_MAX_FRATIO] = {
+ 13500000,
+ 6144000,
+ 6144000,
+ 3072000,
+ 3072000,
+ 2822400,
+ 2822400,
+ 1536000,
+ 1536000,
+ 1536000,
+ 1536000,
+ 1536000,
+ 1536000,
+ 1536000,
+ 1536000,
+ 768000,
+};
+
static struct {
unsigned int min;
unsigned int max;
@@ -2042,16 +2061,32 @@
/* Adjust FRATIO/refdiv to avoid integer mode if possible */
refdiv = cfg->refdiv;
+ arizona_fll_dbg(fll, "pseudo: initial ratio=%u fref=%u refdiv=%u\n",
+ init_ratio, Fref, refdiv);
+
while (div <= ARIZONA_FLL_MAX_REFDIV) {
for (ratio = init_ratio; ratio <= ARIZONA_FLL_MAX_FRATIO;
ratio++) {
if ((ARIZONA_FLL_VCO_CORNER / 2) /
- (fll->vco_mult * ratio) < Fref)
+ (fll->vco_mult * ratio) < Fref) {
+ arizona_fll_dbg(fll, "pseudo: hit VCO corner\n");
break;
+ }
+
+ if (Fref > pseudo_fref_max[ratio - 1]) {
+ arizona_fll_dbg(fll,
+ "pseudo: exceeded max fref(%u) for ratio=%u\n",
+ pseudo_fref_max[ratio - 1],
+ ratio);
+ break;
+ }
if (target % (ratio * Fref)) {
cfg->refdiv = refdiv;
cfg->fratio = ratio - 1;
+ arizona_fll_dbg(fll,
+ "pseudo: found fref=%u refdiv=%d(%d) ratio=%d\n",
+ Fref, refdiv, div, ratio);
return ratio;
}
}
@@ -2060,6 +2095,9 @@
if (target % (ratio * Fref)) {
cfg->refdiv = refdiv;
cfg->fratio = ratio - 1;
+ arizona_fll_dbg(fll,
+ "pseudo: found fref=%u refdiv=%d(%d) ratio=%d\n",
+ Fref, refdiv, div, ratio);
return ratio;
}
}
@@ -2068,6 +2106,9 @@
Fref /= 2;
refdiv++;
init_ratio = arizona_find_fratio(Fref, NULL);
+ arizona_fll_dbg(fll,
+ "pseudo: change fref=%u refdiv=%d(%d) ratio=%u\n",
+ Fref, refdiv, div, init_ratio);
}
arizona_fll_warn(fll, "Falling back to integer mode operation\n");
