[v2] ASoC: fsl_sai: fix no frame clk in master mode
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Message ID af420592483389f5420c573b2b23f187a32baea3.1449717000.git.zidan.wang@freescale.com
State New
Headers show

Commit Message

Zidan Wang Dec. 10, 2015, 3:21 a.m. UTC
After several open/close sai test with ctrl+c, there will be
I/O error. The SAI can't work anymore, can't recover. There
will be no frame clock. With adding the software reset in
trigger stop, the issue can be fixed.

This is a hardware bug/errata and reset is the only option.

According to the reference manual, the software reset doesn't
reset any control register but only internal hardware logics
such as bit clock generator, status flags, and FIFO pointers.
(Our purpose is just to reset the clock generator while the
software reset is the only way to do that.)

Since slave mode doesn't use the clock generator, only apply
the reset procedure to the master mode.

For asynchronous mode, TX will not be reset when RX is still
running. In this case, i can't reproduce this issue.

Signed-off-by: Zidan Wang <zidan.wang@freescale.com>
---

v1->v2:
1) refine the commit log and comments
2) Since slave mode doesn't use the clock generator, only apply
   the reset procedure to the master mode.

 sound/soc/fsl/fsl_sai.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Nicolin Chen Dec. 12, 2015, 4:47 a.m. UTC | #1
On Thu, Dec 10, 2015 at 11:21:25AM +0800, Zidan Wang wrote:

> diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> index 8832901..a55a7de 100644
> --- a/sound/soc/fsl/fsl_sai.c
> +++ b/sound/soc/fsl/fsl_sai.c
> @@ -564,6 +564,17 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
>  					   FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
>  			regmap_update_bits(sai->regmap, FSL_SAI_RCSR,
>  					   FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
> +
> +			if (!sai->is_slave_mode) {

It'd be nicer to add a simple comment to describe the errata here.
Users may have no idea about this abrupt reset as we do.

You may add my ack to your next version:
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>

> +				/* Software Reset for both Tx and Rx */
> +				regmap_write(sai->regmap,
> +					     FSL_SAI_TCSR, FSL_SAI_CSR_SR);
> +				regmap_write(sai->regmap,
> +					     FSL_SAI_RCSR, FSL_SAI_CSR_SR);
> +				/* Clear SR bit to finish the reset */
> +				regmap_write(sai->regmap, FSL_SAI_TCSR, 0);
> +				regmap_write(sai->regmap, FSL_SAI_RCSR, 0);
> +			}

Patch
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diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 8832901..a55a7de 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -564,6 +564,17 @@  static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
 					   FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
 			regmap_update_bits(sai->regmap, FSL_SAI_RCSR,
 					   FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
+
+			if (!sai->is_slave_mode) {
+				/* Software Reset for both Tx and Rx */
+				regmap_write(sai->regmap,
+					     FSL_SAI_TCSR, FSL_SAI_CSR_SR);
+				regmap_write(sai->regmap,
+					     FSL_SAI_RCSR, FSL_SAI_CSR_SR);
+				/* Clear SR bit to finish the reset */
+				regmap_write(sai->regmap, FSL_SAI_TCSR, 0);
+				regmap_write(sai->regmap, FSL_SAI_RCSR, 0);
+			}
 		}
 		break;
 	default: