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ASoC: arizona: Prefer lower FRATIO in pseudo-fractional mode

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When setting up an FLL in pseudo-fractional mode it is preferred
to use a lower FRATIO if possible to give a higher reference clock
frequency. This patch swaps the two loops in arizona_calc_fratio()
so that lower FRATIOs are tried first. The decrementing loop is also
changed to start from init_ratio because the original settings might
already give a fractional value for N.K

Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Richard Fitzgerald 2016-04-21 14:04:14 +01:00 committed by Mark Brown
parent 43b27d7286
commit 8e42db1eaa
1 changed files with 15 additions and 12 deletions
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27
sound/soc/codecs/arizona.c
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@ -2037,7 +2037,21 @@ static int arizona_calc_fratio(struct arizona_fll *fll,
init_ratio, Fref, refdiv); init_ratio, Fref, refdiv);
while (div <= ARIZONA_FLL_MAX_REFDIV) { while (div <= ARIZONA_FLL_MAX_REFDIV) {
for (ratio = init_ratio; ratio <= ARIZONA_FLL_MAX_FRATIO; /* start from init_ratio because this may already give a
* fractional N.K
*/
for (ratio = init_ratio; ratio > 0; ratio--) {
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;
}
}
for (ratio = init_ratio + 1; ratio <= ARIZONA_FLL_MAX_FRATIO;
ratio++) { ratio++) {
if ((ARIZONA_FLL_VCO_CORNER / 2) / if ((ARIZONA_FLL_VCO_CORNER / 2) /
(fll->vco_mult * ratio) < Fref) { (fll->vco_mult * ratio) < Fref) {
@ -2063,17 +2077,6 @@ static int arizona_calc_fratio(struct arizona_fll *fll,
} }
} }
for (ratio = init_ratio - 1; ratio > 0; ratio--) {
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;
}
}
div *= 2; div *= 2;
Fref /= 2; Fref /= 2;
refdiv++; refdiv++;