From c76d572c1ec82e305c97219e28952966958bc31a Mon Sep 17 00:00:00 2001 From: Richard Fitzgerald Date: Thu, 5 Aug 2021 17:11:10 +0100 Subject: [PATCH] ASoC: cs42l42: Assume 24-bit samples are in 32-bit slots 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 Link: https://lore.kernel.org/r/20210805161111.10410-7-rf@opensource.cirrus.com Signed-off-by: Mark Brown --- 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 b2ee514..3677ed4 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) { -- 2.7.4