[alsa-devel] Applied "ASoC: rl6231: Simplify DMIC divider calculation expression" to the asoc tree

[Mark Brown]

The patch

   ASoC: rl6231: Simplify DMIC divider calculation expression

has been applied to the asoc tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From ac1125daf02b81cabb19f35963906335e3d4a155 Mon Sep 17 00:00:00 2001
From: Anatol Pomozov <anatol.pomozov at gmail.com>
Date: Wed, 5 Aug 2015 14:58:33 -0700
Subject: [PATCH] ASoC: rl6231: Simplify DMIC divider calculation expression

Existing implementation checks all divider values and tracks
'red' proximity value for the frequency.

But as divider array is monotonically increasing the first
divider that gives DMIC rate in 3MHz range is the best one
we should use. No need for 'red' zone tracking.

Additionally make sure that DMIC frequency is higher 1MHz.

Signed-off-by: Anatol Pomozov <anatol.pomozov at gmail.com>
Acked-by: Oder Chiou <oder_chiou at realtek.com>
Signed-off-by: Mark Brown <broonie at kernel.org>
---
 sound/soc/codecs/rl6231.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/sound/soc/codecs/rl6231.c b/sound/soc/codecs/rl6231.c
index 57e51c1..aca479f 100644
--- a/sound/soc/codecs/rl6231.c
+++ b/sound/soc/codecs/rl6231.c
@@ -62,31 +62,31 @@ int rl6231_get_pre_div(struct regmap *map, unsigned int reg, int sft)
 EXPORT_SYMBOL_GPL(rl6231_get_pre_div);
 
 /**
- * rl6231_calc_dmic_clk - Calculate the parameter of dmic.
+ * rl6231_calc_dmic_clk - Calculate the frequency divider parameter of dmic.
  *
  * @rate: base clock rate.
  *
- * Choose dmic clock between 1MHz and 3MHz.
- * It is better for clock to approximate 3MHz.
+ * Choose divider parameter that gives the highest possible DMIC frequency in
+ * 1MHz - 3MHz range.
  */
 int rl6231_calc_dmic_clk(int rate)
 {
-	int div[] = {2, 3, 4, 6, 8, 12}, idx = -EINVAL;
-	int i, red, bound, temp;
+	int div[] = {2, 3, 4, 6, 8, 12};
+	int i;
+
+	if (rate < 1000000 * div[0]) {
+		pr_warn("Base clock rate %d is too low\n", rate);
+		return -EINVAL;
+	}
 
-	red = 3000000 * 12;
 	for (i = 0; i < ARRAY_SIZE(div); i++) {
-		bound = div[i] * 3000000;
-		if (rate > bound)
-			continue;
-		temp = bound - rate;
-		if (temp < red) {
-			red = temp;
-			idx = i;
-		}
+		/* find divider that gives DMIC frequency below 3MHz */
+		if (3000000 * div[i] >= rate)
+			return i;
 	}
 
-	return idx;
+	pr_warn("Base clock rate %d is too high\n", rate);
+	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(rl6231_calc_dmic_clk);
 
-- 
2.1.4