If the machine driver doesn't call snd_soc_dai_set_sysclk() the SCLK is assumed to be sample_rate * sample_bits * 2 (that is, the rate necessary for a standard I2S frame).
But 24-bit samples can be sent in either a 24-bit slot or a 32-bit slot. If the PLL is configured for a 24-bit slot, but a 32-bit slot is used, cs42l42 will be overclocked.
Ultimately it is the machine driver's responsibilty to call snd_soc_dai_set_sysclk() if SLK will be different from the standard I2S rate. However, it is convenient to assume 32-bit slots to allow this common case without needing special machine driver support. The machine driver then only has to set SCLK if the slots are 24-bit, but if it fails to do this cs42l42 won't be overclocked.
Signed-off-by: Richard Fitzgerald rf@opensource.cirrus.com --- sound/soc/codecs/cs42l42.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c index b2ee51443a22..3677ed4670d0 100644 --- a/sound/soc/codecs/cs42l42.c +++ b/sound/soc/codecs/cs42l42.c @@ -844,6 +844,13 @@ static int cs42l42_pcm_hw_params(struct snd_pcm_substream *substream, if (channels == 1) cs42l42->bclk *= 2;
+ /* + * Assume 24-bit samples are in 32-bit slots, to prevent SCLK being + * more than assumed (which would result in overclocking). + */ + if (params_width(params) == 24) + cs42l42->bclk = (cs42l42->bclk / 3) * 4; + switch(substream->stream) { case SNDRV_PCM_STREAM_CAPTURE: if (channels == 2) {