[v2,1/2] ASoC: fsl_asrc: make sure the input and output clocks are different
diff mbox series

Message ID 20200716151352.193451-2-arnaud.ferraris@collabora.com
State New
Headers show
Series
  • ASoC: fsl_asrc: improve clock selection and quality
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Commit Message

Arnaud Ferraris July 16, 2020, 3:13 p.m. UTC
The current clock selection algorithm might select the same clock for
both input and output. This can happen when, for instance, the output
sample rate is a multiple of the input rate.

This patch makes sure it always selects distinct input and output
clocks.

Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>
---
 sound/soc/fsl/fsl_asrc.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Comments

Nicolin Chen July 16, 2020, 11:20 p.m. UTC | #1
On Thu, Jul 16, 2020 at 05:13:52PM +0200, Arnaud Ferraris wrote:
> The current clock selection algorithm might select the same clock for
> both input and output. This can happen when, for instance, the output
> sample rate is a multiple of the input rate.

What's the issue when selecting the same clock source for both
input and output? Please explain it in the commit logs.

> This patch makes sure it always selects distinct input and output
> clocks.
> 
> Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>
> ---
>  sound/soc/fsl/fsl_asrc.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/sound/soc/fsl/fsl_asrc.c b/sound/soc/fsl/fsl_asrc.c
> index 02c81d2e34ad..6d43cab6c885 100644
> --- a/sound/soc/fsl/fsl_asrc.c
> +++ b/sound/soc/fsl/fsl_asrc.c
> @@ -608,8 +608,8 @@ static void fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
>  {
>  	struct fsl_asrc_pair_priv *pair_priv = pair->private;
>  	struct asrc_config *config = pair_priv->config;
> -	int rate[2], select_clk[2]; /* Array size 2 means IN and OUT */
> -	int clk_rate, clk_index;
> +	int rate[2], select_clk[2], clk_index[2]; /* Array size 2 means IN and OUT */
> +	int clk_rate;
>  	int i = 0, j = 0;
>  
>  	rate[IN] = in_rate;
> @@ -618,11 +618,12 @@ static void fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
>  	/* Select proper clock source for internal ratio mode */
>  	for (j = 0; j < 2; j++) {
>  		for (i = 0; i < ASRC_CLK_MAP_LEN; i++) {
> -			clk_index = asrc_priv->clk_map[j][i];
> -			clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index]);
> +			clk_index[j] = asrc_priv->clk_map[j][i];
> +			clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index[j]]);
>  			/* Only match a perfect clock source with no remainder */

Better to update the comments here as there's a new condition.

>  			if (clk_rate != 0 && (clk_rate / rate[j]) <= 1024 &&
> -			    (clk_rate % rate[j]) == 0)
> +			    (clk_rate % rate[j]) == 0 &&
> +			    (j == 0 || clk_index[j] != clk_index[j-1]))

clk_index[j - 1]

Patch
diff mbox series

diff --git a/sound/soc/fsl/fsl_asrc.c b/sound/soc/fsl/fsl_asrc.c
index 02c81d2e34ad..6d43cab6c885 100644
--- a/sound/soc/fsl/fsl_asrc.c
+++ b/sound/soc/fsl/fsl_asrc.c
@@ -608,8 +608,8 @@  static void fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
 {
 	struct fsl_asrc_pair_priv *pair_priv = pair->private;
 	struct asrc_config *config = pair_priv->config;
-	int rate[2], select_clk[2]; /* Array size 2 means IN and OUT */
-	int clk_rate, clk_index;
+	int rate[2], select_clk[2], clk_index[2]; /* Array size 2 means IN and OUT */
+	int clk_rate;
 	int i = 0, j = 0;
 
 	rate[IN] = in_rate;
@@ -618,11 +618,12 @@  static void fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
 	/* Select proper clock source for internal ratio mode */
 	for (j = 0; j < 2; j++) {
 		for (i = 0; i < ASRC_CLK_MAP_LEN; i++) {
-			clk_index = asrc_priv->clk_map[j][i];
-			clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index]);
+			clk_index[j] = asrc_priv->clk_map[j][i];
+			clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index[j]]);
 			/* Only match a perfect clock source with no remainder */
 			if (clk_rate != 0 && (clk_rate / rate[j]) <= 1024 &&
-			    (clk_rate % rate[j]) == 0)
+			    (clk_rate % rate[j]) == 0 &&
+			    (j == 0 || clk_index[j] != clk_index[j-1]))
 				break;
 		}