[alsa-devel] Low sample rates for SGTL5000 on i.MX28

[Fabio Estevam]

On Thu, Nov 13, 2014 at 10:29 PM, Fabio Estevam <festevam at gmail.com> wrote:

> Ok, so the 'aplay stereo_8k.wav' is converting the rate to 44.1kHz, so
> that's why it does not fail.

>From the sgtl5000 datasheet, it looks like the MCLK range of 8 to
27MHz limitation does not apply when sgtl5000 runs in slave mode.

A quick hack that allows 'aplay -D hw:0,0 stereo_8k.wav' to play:

diff --git a/sound/soc/codecs/sgtl5000.c b/sound/soc/codecs/sgtl5000.c
index 6bb77d7..4a329b0 100644
--- a/sound/soc/codecs/sgtl5000.c
+++ b/sound/soc/codecs/sgtl5000.c
@@ -623,13 +623,6 @@ static int sgtl5000_set_clock(struct snd_soc_codec *codec,
                if (sgtl5000->master) {
                        clk_ctl |= SGTL5000_MCLK_FREQ_PLL <<
diff --git a/sound/soc/codecs/sgtl5000.c b/sound/soc/codecs/sgtl5000.c
index 6bb77d7..4a329b0 100644
--- a/sound/soc/codecs/sgtl5000.c
+++ b/sound/soc/codecs/sgtl5000.c
@@ -623,13 +623,6 @@ static int sgtl5000_set_clock(struct snd_soc_codec *codec,
                if (sgtl5000->master) {
                        clk_ctl |= SGTL5000_MCLK_FREQ_PLL <<
                                SGTL5000_MCLK_FREQ_SHIFT;
-               } else {
-                       dev_err(codec->dev,
-                               "PLL not supported in slave mode\n");
-                       dev_err(codec->dev, "%d ratio is not supported. "
-                               "SYS_MCLK needs to be 256, 384 or 512 * fs\n",
-                               sgtl5000->sysclk / sys_fs);
-                       return -EINVAL;
                }
        }

@@ -1417,7 +1410,6 @@ static int sgtl5000_i2c_probe(struct i2c_client *client,
 {
        struct sgtl5000_priv *sgtl5000;
        int ret, reg, rev;
-       unsigned int mclk;

        sgtl5000 = devm_kzalloc(&client->dev, sizeof(struct sgtl5000_priv),
                                                                GFP_KERNEL);
@@ -1441,14 +1433,6 @@ static int sgtl5000_i2c_probe(struct i2c_client *client,
                return ret;
        }

-       /* SGTL5000 SYS_MCLK should be between 8 and 27 MHz */
-       mclk = clk_get_rate(sgtl5000->mclk);
-       if (mclk < 8000000 || mclk > 27000000) {
-               dev_err(&client->dev, "Invalid SYS_CLK frequency: %u.%03uMHz\n",
-                       mclk / 1000000, mclk / 1000 % 1000);
-               return -EINVAL;
-       }
-
        ret = clk_prepare_enable(sgtl5000->mclk);
        if (ret)
                return ret;
diff --git a/sound/soc/mxs/mxs-sgtl5000.c b/sound/soc/mxs/mxs-sgtl5000.c
index 61822cc..3bba6cf 100644
--- a/sound/soc/mxs/mxs-sgtl5000.c
+++ b/sound/soc/mxs/mxs-sgtl5000.c
@@ -49,13 +49,6 @@ static int mxs_sgtl5000_hw_params(struct snd_pcm_substream *s
                break;
        }

-       /* Sgtl5000 sysclk should be >= 8MHz and <= 27M */
-       if (mclk < 8000000 || mclk > 27000000) {
-               dev_err(codec_dai->dev, "Invalid mclk frequency: %u.%03uMHz\n",
-                       mclk / 1000000, mclk / 1000 % 1000);
-               return -EINVAL;
-       }
-
        /* Set SGTL5000's SYSCLK (provided by SAIF MCLK) */
        ret = snd_soc_dai_set_sysclk(codec_dai, SGTL5000_SYSCLK, mclk, 0);
        if (ret) {