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ASoC: cs42l42: Don't reconfigure the PLL while it is running 

When capture and playback substreams are both running at the same time,
cs42l42_pcm_hw_params() would be called for each direction. The first
call will configure the PLL. The second call must not write the PLL
configuration registers again if the first substream is already running,
as this could destabilize the PLL.

The DAI is marked symmetric sample bits and sample rate, so the two
directions will always have the same SCLK (I2S always has 2 channel slots
so the DAI does not need to require symmetric channels to guarantee the
same SCLK). However, since cs42l42_pll_config() is checking for an active
stream it may as well test that the requested SCLK is the same as the
currently active configuration.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20211015133619.4698-2-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Richard Fitzgerald 2021-10-15 14:36:04 +01:00 committed by Mark Brown
parent 6b9b546dc0
commit 06441c82f0
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1 changed files with 8 additions and 0 deletions
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8
sound/soc/codecs/cs42l42.c
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@ -618,6 +618,14 @@ static int cs42l42_pll_config(struct snd_soc_component *component)
else
clk = cs42l42->sclk;
/* Don't reconfigure if there is an audio stream running */
if (cs42l42->stream_use) {
if (pll_ratio_table[cs42l42->pll_config].sclk == clk)
return 0;
else
return -EBUSY;
}
for (i = 0; i < ARRAY_SIZE(pll_ratio_table); i++) {
if (pll_ratio_table[i].sclk == clk) {
cs42l42->pll_config = i;