Re: [PATCH] ASoC: fsl_sai: Set SAI Channel Mode to Output Mode

On Thu, Sep 3, 2020 at 11:42 AM Nicolin Chen [off-list ref] wrote:

On Thu, Sep 03, 2020 at 11:09:15AM +0800, Shengjiu Wang wrote:

quoted

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 <redacted>
Signed-off-by: Shengjiu Wang <redacted>

Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>

Though one nit inline:

quoted

---
 sound/soc/fsl/fsl_sai.c | 12 ++++++++++--
 sound/soc/fsl/fsl_sai.h |  2 ++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 62c5fdb678fc..33b194a5c1dc 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c

@@ -486,6 +486,12 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,

      val_cr4 |= FSL_SAI_CR4_FRSZ(slots);

+     /* Output Mode - data pins transmit 0 when slots are masked
+      * or channels are disabled
+      */

Coding style for multi-line comments. Yet, probably can simplify?

        /* Set to output mode to avoid tri-stated data pins */

Ok, will update in v2.

best regards
wang shengjiu