linux-kernel - [PATCH 14/25] ASoC: sun8i-codec: Correct the BCLK divisor calculation

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Message-Id: <20201001021148.15852-15-samuel@sholland.org>
Date:   Wed, 30 Sep 2020 21:11:37 -0500
From:   Samuel Holland <samuel@...lland.org>
To:     Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>, Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>
Cc:     Ondrej Jirman <megous@...ous.com>, alsa-devel@...a-project.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Samuel Holland <samuel@...lland.org>
Subject: [PATCH 14/25] ASoC: sun8i-codec: Correct the BCLK divisor calculation

Previously, the BCLK divisor calculation assumed a power-of-two slot
width and exactly two slots. In order to support the TDM slot binding
and 20/24-bit word sizes, those assumptions must be removed.

Due to hardware limitations, the BCLK/LRCK ratio is not as simple as
"slot_width * slots". However, the correct value is already calculated
elsewhere in this function, since it must also be programmed into the
hardware. Reuse that value to calculate the correct SYSCLK/BCLK divisor.

Signed-off-by: Samuel Holland <samuel@...lland.org>
---
 sound/soc/sunxi/sun8i-codec.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/sound/soc/sunxi/sun8i-codec.c b/sound/soc/sunxi/sun8i-codec.c
index 779853d023fe..78feed37aa42 100644
--- a/sound/soc/sunxi/sun8i-codec.c
+++ b/sound/soc/sunxi/sun8i-codec.c
@@ -279,21 +279,21 @@ static const struct sun8i_codec_clk_div sun8i_codec_bclk_div[] = {
 	{ .div = 48,	.val = 9 },
 	{ .div = 64,	.val = 10 },
 	{ .div = 96,	.val = 11 },
 	{ .div = 128,	.val = 12 },
 	{ .div = 192,	.val = 13 },
 };
 
 static u8 sun8i_codec_get_bclk_div(struct sun8i_codec *scodec,
-				   unsigned int rate,
-				   unsigned int word_size)
+				   unsigned int lrck_div_order,
+				   unsigned int sample_rate)
 {
 	unsigned long clk_rate = clk_get_rate(scodec->clk_module);
-	unsigned int div = clk_rate / rate / word_size / 2;
+	unsigned int div = clk_rate / sample_rate >> lrck_div_order;
 	unsigned int best_val = 0, best_diff = ~0;
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(sun8i_codec_bclk_div); i++) {
 		const struct sun8i_codec_clk_div *bdiv = &sun8i_codec_bclk_div[i];
 		unsigned int diff = abs(bdiv->div - div);
 
 		if (diff < best_diff) {
@@ -343,30 +343,31 @@ static int sun8i_codec_hw_params(struct snd_pcm_substream *substream,
 	default:
 		return -EINVAL;
 	}
 
 	regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
 			   SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ_MASK,
 			   word_size << SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ);
 
-	bclk_div = sun8i_codec_get_bclk_div(scodec, params_rate(params), 16);
-	regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
-			   SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV_MASK,
-			   bclk_div << SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV);
-
 	/* LRCK divider (BCLK/LRCK ratio) */
 	lrck_div_order = sun8i_codec_get_lrck_div_order(slots, slot_width);
 	if (lrck_div_order < 0)
 		return lrck_div_order;
 
 	regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
 			   SUN8I_AIF1CLK_CTRL_AIF1_LRCK_DIV_MASK,
 			   (lrck_div_order - 4) << SUN8I_AIF1CLK_CTRL_AIF1_LRCK_DIV);
 
+	/* BCLK divider (SYSCLK/BCLK ratio) */
+	bclk_div = sun8i_codec_get_bclk_div(scodec, lrck_div_order, params_rate(params));
+	regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
+			   SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV_MASK,
+			   bclk_div << SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV);
+
 	sample_rate = sun8i_codec_get_hw_rate(params);
 	if (sample_rate < 0)
 		return sample_rate;
 
 	regmap_update_bits(scodec->regmap, SUN8I_SYS_SR_CTRL,
 			   SUN8I_SYS_SR_CTRL_AIF1_FS_MASK,
 			   sample_rate << SUN8I_SYS_SR_CTRL_AIF1_FS);
 
-- 
2.26.2