Transmit data pins will output zero when slots are masked or channels
are disabled. In CHMOD TDM mode, transmit data pins are tri-stated when
slots are masked or channels are disabled. When data pins are tri-stated,
there is noise on some channels when FS clock value is high and data is
read while fsclk is transitioning from high to low.
Signed-off-by: Cosmin-Gabriel Samoila <[email protected]>
Signed-off-by: Shengjiu Wang <[email protected]>
Acked-by: Nicolin Chen <[email protected]>
---
changes in v2
- update note
- add acked-by Nicolin
sound/soc/fsl/fsl_sai.c | 10 ++++++++--
sound/soc/fsl/fsl_sai.h | 2 ++
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 38c7bcbb361d..b2d65e53dbc4 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -489,6 +489,10 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
val_cr4 |= FSL_SAI_CR4_FRSZ(slots);
+ /* Set to output mode to avoid tri-stated data pins */
+ if (tx)
+ val_cr4 |= FSL_SAI_CR4_CHMOD;
+
/*
* For SAI master mode, when Tx(Rx) sync with Rx(Tx) clock, Rx(Tx) will
* generate bclk and frame clock for Tx(Rx), we should set RCR4(TCR4),
@@ -497,7 +501,8 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
if (!sai->is_slave_mode && fsl_sai_dir_is_synced(sai, adir)) {
regmap_update_bits(sai->regmap, FSL_SAI_xCR4(!tx, ofs),
- FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK,
+ FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK |
+ FSL_SAI_CR4_CHMOD_MASK,
val_cr4);
regmap_update_bits(sai->regmap, FSL_SAI_xCR5(!tx, ofs),
FSL_SAI_CR5_WNW_MASK | FSL_SAI_CR5_W0W_MASK |
@@ -508,7 +513,8 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
FSL_SAI_CR3_TRCE_MASK,
FSL_SAI_CR3_TRCE((1 << pins) - 1));
regmap_update_bits(sai->regmap, FSL_SAI_xCR4(tx, ofs),
- FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK,
+ FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK |
+ FSL_SAI_CR4_CHMOD_MASK,
val_cr4);
regmap_update_bits(sai->regmap, FSL_SAI_xCR5(tx, ofs),
FSL_SAI_CR5_WNW_MASK | FSL_SAI_CR5_W0W_MASK |
diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
index 5f630be74853..736a437450c8 100644
--- a/sound/soc/fsl/fsl_sai.h
+++ b/sound/soc/fsl/fsl_sai.h
@@ -119,6 +119,8 @@
#define FSL_SAI_CR4_FRSZ_MASK (0x1f << 16)
#define FSL_SAI_CR4_SYWD(x) (((x) - 1) << 8)
#define FSL_SAI_CR4_SYWD_MASK (0x1f << 8)
+#define FSL_SAI_CR4_CHMOD BIT(5)
+#define FSL_SAI_CR4_CHMOD_MASK BIT(5)
#define FSL_SAI_CR4_MF BIT(4)
#define FSL_SAI_CR4_FSE BIT(3)
#define FSL_SAI_CR4_FSP BIT(1)
--
2.27.0
On Thu, 3 Sep 2020 13:53:47 +0800, Shengjiu Wang wrote:
> Transmit data pins will output zero when slots are masked or channels
> are disabled. In CHMOD TDM mode, transmit data pins are tri-stated when
> slots are masked or channels are disabled. When data pins are tri-stated,
> there is noise on some channels when FS clock value is high and data is
> read while fsclk is transitioning from high to low.
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next
Thanks!
[1/1] ASoC: fsl_sai: Set SAI Channel Mode to Output Mode
commit: f4c4b1bb2f5a7f034f039c302b56f82344a6dc8c
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