ASoC: cs4270: allow passing freq=0 in set_dai_sysclk()

For setups with variable MCLKs, the current logic of limiting the
available sampling rates at startup time is not sufficient. We need to
be able to change the setting at a later point, and so the codec must
offer all possible rates until the hw_params are given.

This patches allows that by passing 0 as 'freq' argument to
cs4270_set_dai_sysclk().

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 25 insertions, 13 deletions

diff --git a/sound/soc/codecs/cs4270.c b/sound/soc/codecs/cs4270.c
index 8b5457542a0e..593bfc7a6986 100644
--- a/sound/soc/codecs/cs4270.c
+++ b/sound/soc/codecs/cs4270.c
@@ -200,6 +200,11 @@ static struct cs4270_mode_ratios cs4270_mode_ratios[] = {
  * This function must be called by the machine driver's 'startup' function,
  * otherwise the list of supported sample rates will not be available in
  * time for ALSA.
+ *
+ * For setups with variable MCLKs, pass 0 as 'freq' argument. This will cause
+ * theoretically possible sample rates to be enabled. Call it again with a
+ * proper value set one the external clock is set (most probably you would do
+ * that from a machine's driver 'hw_param' hook.
  */
 static int cs4270_set_dai_sysclk(struct snd_soc_dai *codec_dai,
                                  int clk_id, unsigned int freq, int dir)
@@ -213,20 +218,27 @@ static int cs4270_set_dai_sysclk(struct snd_soc_dai *codec_dai,
 
         cs4270->mclk = freq;
 
-        for (i = 0; i < NUM_MCLK_RATIOS; i++) {
-                unsigned int rate = freq / cs4270_mode_ratios[i].ratio;
-                rates |= snd_pcm_rate_to_rate_bit(rate);
-                if (rate < rate_min)
-                        rate_min = rate;
-                if (rate > rate_max)
-                        rate_max = rate;
-        }
-        /* FIXME: soc should support a rate list */
-        rates &= ~SNDRV_PCM_RATE_KNOT;
+        if (cs4270->mclk) {
+                for (i = 0; i < NUM_MCLK_RATIOS; i++) {
+                        unsigned int rate = freq / cs4270_mode_ratios[i].ratio;
+                        rates |= snd_pcm_rate_to_rate_bit(rate);
+                        if (rate < rate_min)
+                                rate_min = rate;
+                        if (rate > rate_max)
+                                rate_max = rate;
+                }
+                /* FIXME: soc should support a rate list */
+                rates &= ~SNDRV_PCM_RATE_KNOT;
 
-        if (!rates) {
-                dev_err(codec->dev, "could not find a valid sample rate\n");
-                return -EINVAL;
+                if (!rates) {
+                        dev_err(codec->dev, "could not find a valid sample rate\n");
+                        return -EINVAL;
+                }
+        } else {
+                /* enable all possible rates */
+                rates = SNDRV_PCM_RATE_8000_192000;
+                rate_min = 8000;
+                rate_max = 192000;
         }
 
         codec_dai->playback.rates = rates;