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

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>

diff --git a/sound/soc/codecs/arizona.c b/sound/soc/codecs/arizona.c
index d8a6823..0caecc6 100644 (file)
--- a/sound/soc/codecs/arizona.c
+++ b/sound/soc/codecs/arizona.c
@@ -2037,7 +2037,21 @@ static int arizona_calc_fratio(struct arizona_fll *fll,
                        init_ratio, Fref, 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++) {
                        if ((ARIZONA_FLL_VCO_CORNER / 2) /
                            (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;
                Fref /= 2;
                refdiv++;