ASoC: fsl_sai: use DIV_ROUND_CLOSEST() to calculate divider

In fsl_sai_set_bclk() we want to calculate the divider that gets us
closest to the desired frequency, so use DIV_ROUND_CLOSEST() instead of
just doing a clk_rate/freq.
Also discard invalid ratios earlier.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20220302083428.3804687-7-s.hauer@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 02b4cff..761fa82 100644 (file)
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -366,9 +366,11 @@ static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
                if (!clk_rate)
                        continue;
 
-               ratio = clk_rate / freq;
+               ratio = DIV_ROUND_CLOSEST(clk_rate, freq);
+               if (!ratio || ratio > 512 || ratio & 1)
+                       continue;
 
-               diff = clk_rate - ratio * freq;
+               diff = abs((long)clk_rate - ratio * freq);
 
                /*
                 * Drop the source that can not be
@@ -381,10 +383,6 @@ static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
                        "ratio %d for freq %dHz based on clock %ldHz\n",
                        ratio, freq, clk_rate);
 
-               if (ratio % 2 == 0 && ratio >= 2 && ratio <= 512)
-                       ratio /= 2;
-               else
-                       continue;
 
                if (diff < bestdiff) {
                        savediv = ratio;
@@ -424,7 +422,7 @@ static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
 
        regmap_update_bits(sai->regmap, reg, FSL_SAI_CR2_MSEL_MASK,
                           FSL_SAI_CR2_MSEL(sai->mclk_id[tx]));
-       regmap_update_bits(sai->regmap, reg, FSL_SAI_CR2_DIV_MASK, savediv - 1);
+       regmap_update_bits(sai->regmap, reg, FSL_SAI_CR2_DIV_MASK, savediv / 2 - 1);
 
        return 0;
 }