2016-09-10 12:54:26 +00:00
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From fb1dbd3a7ff1ae0ccd429a4decafc882473f5d94 Mon Sep 17 00:00:00 2001
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2016-01-17 10:42:23 +00:00
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From: Matthias Reichl <hias@horus.com>
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Date: Sun, 11 Oct 2015 15:21:16 +0200
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2016-09-10 12:54:26 +00:00
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Subject: [PATCH] bcm2835-i2s: add 24bit support, update bclk_ratio to more
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correct values
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2016-01-17 10:42:23 +00:00
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Code ported from bcm2708-i2s driver in Raspberry Pi tree.
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RPi commit 62c05a0b5328d9376d39c9e74da10b8a2465c234 ("ASoC: BCM2708:
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Add 24 bit support")
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This adds 24 bit support to the I2S driver of the BCM2708.
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Besides enabling the 24 bit flags, it includes two bug fixes:
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MMAP is not supported. Claiming this leads to strange issues
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when the format of driver and file do not match.
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The datasheet states that the width extension bit should be set
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for widths greater than 24, but greater or equal would be correct.
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This follows from the definition of the width field.
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Signed-off-by: Florian Meier <florian.meier@koalo.de>
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RPi commit 3e8c672bc4e92d457aa4654bbb4cfd79a18a2327 ("bcm2708-i2s:
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Update bclk_ratio to more correct values")
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Discussion about blck_ratio affecting sound quality:
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https://github.com/raspberrypi/linux/issues/681
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Signed-off-by: Matthias Reichl <hias@horus.com>
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---
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sound/soc/bcm/bcm2835-i2s.c | 12 +++++++++---
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1 file changed, 9 insertions(+), 3 deletions(-)
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--- a/sound/soc/bcm/bcm2835-i2s.c
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+++ b/sound/soc/bcm/bcm2835-i2s.c
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@@ -340,11 +340,15 @@ static int bcm2835_i2s_hw_params(struct
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switch (params_format(params)) {
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case SNDRV_PCM_FORMAT_S16_LE:
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data_length = 16;
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- bclk_ratio = 40;
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+ bclk_ratio = 50;
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+ break;
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+ case SNDRV_PCM_FORMAT_S24_LE:
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+ data_length = 24;
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+ bclk_ratio = 50;
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break;
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case SNDRV_PCM_FORMAT_S32_LE:
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data_length = 32;
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- bclk_ratio = 80;
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+ bclk_ratio = 100;
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break;
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default:
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return -EINVAL;
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@@ -420,7 +424,7 @@ static int bcm2835_i2s_hw_params(struct
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/* Setup the frame format */
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format = BCM2835_I2S_CHEN;
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- if (data_length > 24)
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+ if (data_length >= 24)
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format |= BCM2835_I2S_CHWEX;
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format |= BCM2835_I2S_CHWID((data_length-8)&0xf);
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@@ -711,6 +715,7 @@ static struct snd_soc_dai_driver bcm2835
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.channels_max = 2,
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.rates = SNDRV_PCM_RATE_8000_192000,
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.formats = SNDRV_PCM_FMTBIT_S16_LE
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+ | SNDRV_PCM_FMTBIT_S24_LE
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| SNDRV_PCM_FMTBIT_S32_LE
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},
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.capture = {
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@@ -718,6 +723,7 @@ static struct snd_soc_dai_driver bcm2835
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.channels_max = 2,
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.rates = SNDRV_PCM_RATE_8000_192000,
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.formats = SNDRV_PCM_FMTBIT_S16_LE
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+ | SNDRV_PCM_FMTBIT_S24_LE
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| SNDRV_PCM_FMTBIT_S32_LE
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},
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.ops = &bcm2835_i2s_dai_ops,
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