linux-kernel - [PATCH v2 1/2] ASoC: fsl_asrc: make sure the input and output clocks are different

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Message-Id: <20200716151352.193451-2-arnaud.ferraris@collabora.com>
Date:   Thu, 16 Jul 2020 17:13:52 +0200
From:   Arnaud Ferraris <arnaud.ferraris@...labora.com>
To:     alsa-devel@...a-project.org
Cc:     Timur Tabi <timur@...nel.org>,
        Nicolin Chen <nicoleotsuka@...il.com>,
        Xiubo Li <Xiubo.Lee@...il.com>,
        Fabio Estevam <festevam@...il.com>,
        Shengjiu Wang <shengjiu.wang@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
        kernel@...labora.com,
        Arnaud Ferraris <arnaud.ferraris@...labora.com>
Subject: [PATCH v2 1/2] ASoC: fsl_asrc: make sure the input and output clocks are different

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@...labora.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 */
 			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;
 		}
 
-- 
2.27.0