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ASoC: tegra: use sample size of 32 for S24_LE

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I2S bit clock is derived from PLLA_OUT0 and sample size of 24 bits
results in fractional value. Clock is not accurate because of this
and noisy playback is observed. To avoid this sample size of 32 bits
can be used to derive I2S bit clock. This means there are additional
bit clocks (8 cycles) per channel which are ignored. Codec picks up
data for the other channel when LRCK toggles. The same is true for
capture as well.

For I2S Tegra-Slave mode this problem is not seen because the clock
signals are driven from the codec and above fix is not necessary for
it.

Bug 200594265
Bug 2845498

Change-Id: Ifa17e65a814fab060ab4762d19edfe34420524ce
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2303591
(cherry picked from commit 1bc9e1904454b359361da6682517952fd0108b46)
Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-5.4/+/2312716
Reviewed-by: automaticguardword <automaticguardword@nvidia.com>
Reviewed-by: Mohan Kumar D <mkumard@nvidia.com>
Reviewed-by: Sharad Gupta <sharadg@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
This commit is contained in:
Sameer Pujar
2020-03-14 19:54:32 +05:30
parent 0978d6b988
commit d7c5b86e51
1 changed files with 11 additions and 1 deletions
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12
sound/soc/tegra/tegra210_i2s.c
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@@ -539,7 +539,17 @@ static int tegra210_i2s_hw_params(struct snd_pcm_substream *substream,
break;
case SNDRV_PCM_FORMAT_S24_LE:
val = I2S_BITS_24;
sample_size = 24;
/*
* I2S bit clock is derived from PLLA_OUT0 and size of
* 24 bits results in fractional value and the clock
* is not accurate with this. To have integer clock
* division below is used. It means there are additional
* bit clocks (8 cycles) which are ignored. Codec picks
* up data for other channel when LRCK signal toggles.
*/
sample_size = 32;
cif_conf.audio_bits = TEGRA_ACIF_BITS_24;
cif_conf.client_bits = TEGRA_ACIF_BITS_24;
break;