ASoC: arizona: Fixed a bug in FLL fractional calculation

Previously arizona_calc_fll() was checking if the target frequency is
exactly divisible by reference frequency, but should have been product
of the ratio and the reference frequency.

Also scale down the Lamba and Theta coefficients be under 16-bits in
order to match the registers.

Signed-off-by: Ryo Tsutsui <ryo.tsutsui@wolfsonmicro.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org

diff --git a/sound/soc/codecs/arizona.c b/sound/soc/codecs/arizona.c
index ef62c43..2899cb9 100644 (file)
--- a/sound/soc/codecs/arizona.c
+++ b/sound/soc/codecs/arizona.c
@@ -910,7 +910,7 @@ static int arizona_calc_fll(struct arizona_fll *fll,
 
        cfg->n = target / (ratio * Fref);
 
-       if (target % Fref) {
+       if (target % (ratio * Fref)) {
                gcd_fll = gcd(target, ratio * Fref);
                arizona_fll_dbg(fll, "GCD=%u\n", gcd_fll);
 
@@ -922,6 +922,15 @@ static int arizona_calc_fll(struct arizona_fll *fll,
                cfg->lambda = 0;
        }
 
+       /* Round down to 16bit range with cost of accuracy lost.
+        * Denominator must be bigger than numerator so we only
+        * take care of it.
+        */
+       while (cfg->lambda >= (1 << 16)) {
+               cfg->theta >>= 1;
+               cfg->lambda >>= 1;
+       }
+
        arizona_fll_dbg(fll, "N=%x THETA=%x LAMBDA=%x\n",
                        cfg->n, cfg->theta, cfg->lambda);
        arizona_fll_dbg(fll, "FRATIO=%x(%d) OUTDIV=%x REFCLK_DIV=%x\n",