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ASoC: bcm2835: fix hw_params error when device is in prepared state

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If bcm2835 is configured as bitclock master calling hw_params()
after prepare() fails with EBUSY. This also makes it impossible to
use bcm2835 in full duplex mode.

The error is caused by the split clock setup: clk_set_rate
is called in hw_params, clk_prepare_enable in prepare. As hw_params
doesn't check if the clock was already enabled clk_set_rate
fails with EBUSY.

Fix this by moving clock startup from prepare to hw_params and
let hw_params properly deal with an already set up or enabled
clock.

Signed-off-by: Matthias Reichl <hias@horus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Matthias Reichl 2018-01-17 13:50:50 +01:00 committed by Mark Brown
parent 4fbd8d194f
commit 8d5737a5f5
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GPG Key ID: 24D68B725D5487D0
1 changed files with 14 additions and 6 deletions
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20
sound/soc/bcm/bcm2835-i2s.c
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@ -130,6 +130,7 @@ struct bcm2835_i2s_dev {
struct regmap *i2s_regmap;
struct clk *clk;
bool clk_prepared;
int clk_rate;
};
static void bcm2835_i2s_start_clock(struct bcm2835_i2s_dev *dev)
@ -419,10 +420,19 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream,
}
/* Clock should only be set up here if CPU is clock master */
if (bit_clock_master) {
ret = clk_set_rate(dev->clk, bclk_rate);
if (ret)
return ret;
if (bit_clock_master &&
(!dev->clk_prepared || dev->clk_rate != bclk_rate)) {
if (dev->clk_prepared)
bcm2835_i2s_stop_clock(dev);
if (dev->clk_rate != bclk_rate) {
ret = clk_set_rate(dev->clk, bclk_rate);
if (ret)
return ret;
dev->clk_rate = bclk_rate;
}
bcm2835_i2s_start_clock(dev);
}
/* Setup the frame format */
@ -618,8 +628,6 @@ static int bcm2835_i2s_prepare(struct snd_pcm_substream *substream,
struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
uint32_t cs_reg;
bcm2835_i2s_start_clock(dev);
/*
* Clear both FIFOs if the one that should be started
* is not empty at the moment. This should only happen