[alsa-devel] Applied "ASoC: sun4i-i2s: Don't use the oversample to calculate BCLK" to the asoc tree

[Mark Brown]

The patch

   ASoC: sun4i-i2s: Don't use the oversample to calculate BCLK

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-5.4

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 7df8f9a20196072162d9dc8fe99943f2d35f23d5 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime.ripard at bootlin.com>
Date: Mon, 19 Aug 2019 21:25:14 +0200
Subject: [PATCH] ASoC: sun4i-i2s: Don't use the oversample to calculate BCLK

The BCLK divider should be calculated using the parameters that actually
make the BCLK rate: the number of channels, the sampling rate and the
sample width.

We've been using the oversample_rate previously because in the former SoCs,
the BCLK's parent is MCLK, which in turn is being used to generate the
oversample rate, so we end up with something like this:

oversample = mclk_rate / sampling_rate
bclk_div = oversample / word_size / channels

So, bclk_div = mclk_rate / sampling_rate / word_size / channels.

And this is actually better, since the oversampling ratio only plays a role
because the MCLK is its parent, not because of what BCLK is supposed to be.

Furthermore, that assumption of MCLK being the parent has been broken on
newer SoCs, so let's use the proper formula, and have the parent rate as an
argument.

Fixes: 7d2993811a1e ("ASoC: sun4i-i2s: Add support for H3")
Fixes: 21faaea1343f ("ASoC: sun4i-i2s: Add support for A83T")
Fixes: 66ecce332538 ("ASoC: sun4i-i2s: Add compatibility with A64 codec I2S")
Signed-off-by: Maxime Ripard <maxime.ripard at bootlin.com>
Link: https://lore.kernel.org/r/c3595e3a9788c2ef2dcc30aa3c8c4953bb5cc249.1566242458.git-series.maxime.ripard@bootlin.com
Signed-off-by: Mark Brown <broonie at kernel.org>
---
 sound/soc/sunxi/sun4i-i2s.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
index 70608fa30bf2..d879db581073 100644
--- a/sound/soc/sunxi/sun4i-i2s.c
+++ b/sound/soc/sunxi/sun4i-i2s.c
@@ -222,10 +222,11 @@ static const struct sun4i_i2s_clk_div sun4i_i2s_mclk_div[] = {
 };
 
 static int sun4i_i2s_get_bclk_div(struct sun4i_i2s *i2s,
-				  unsigned int oversample_rate,
+				  unsigned long parent_rate,
+				  unsigned int sampling_rate,
 				  unsigned int word_size)
 {
-	int div = oversample_rate / word_size / 2;
+	int div = parent_rate / sampling_rate / word_size / 2;
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(sun4i_i2s_bclk_div); i++) {
@@ -315,8 +316,8 @@ static int sun4i_i2s_set_clk_rate(struct snd_soc_dai *dai,
 		return -EINVAL;
 	}
 
-	bclk_div = sun4i_i2s_get_bclk_div(i2s, oversample_rate,
-					  word_size);
+	bclk_div = sun4i_i2s_get_bclk_div(i2s, i2s->mclk_freq,
+					  rate, word_size);
 	if (bclk_div < 0) {
 		dev_err(dai->dev, "Unsupported BCLK divider: %d\n", bclk_div);
 		return -EINVAL;
-- 
2.20.1