@@ -245,13 +245,14 @@ static const unsigned short logtable[256] = {
* tasks are allowed to acquire the semaphore, calling this function will
* put the task to sleep. If the semaphore is not released within the
* specified number of jiffies, this function returns.
- * Acquires the semaphore without jiffies. If no more tasks are allowed
- * to acquire the semaphore, calling this function will put the task to
- * sleep until the semaphore is released.
* If the semaphore is not released within the specified number of jiffies,
- * this function returns -ETIME.
- * If the sleep is interrupted by a signal, this function will return -EINTR.
- * It returns 0 if the semaphore was acquired successfully.
+ * this function returns -ETIME. If the sleep is interrupted by a signal,
+ * this function will return -EINTR. It returns 0 if the semaphore was
+ * acquired successfully.
+ *
+ * Acquires the semaphore without jiffies. Try to acquire the semaphore
+ * atomically. Returns 0 if the semaphore has been acquired successfully
+ * or 1 if it it cannot be acquired.
*/
static int nau8825_sema_acquire(struct nau8825 *nau8825, long timeout)
{
@@ -262,8 +263,8 @@ static int nau8825_sema_acquire(struct nau8825 *nau8825, long timeout)
if (ret < 0)
dev_warn(nau8825->dev, "Acquire semaphore timeout\n");
} else {
- ret = down_interruptible(&nau8825->xtalk_sem);
- if (ret < 0)
+ ret = down_trylock(&nau8825->xtalk_sem);
+ if (ret)
dev_warn(nau8825->dev, "Acquire semaphore fail\n");
}
@@ -1258,8 +1259,10 @@ static int nau8825_hw_params(struct snd_pcm_substream *substream,
regmap_read(nau8825->regmap, NAU8825_REG_DAC_CTRL1, &osr);
osr &= NAU8825_DAC_OVERSAMPLE_MASK;
if (nau8825_clock_check(nau8825, substream->stream,
- params_rate(params), osr))
+ params_rate(params), osr)) {
+ nau8825_sema_release(nau8825);
return -EINVAL;
+ }
regmap_update_bits(nau8825->regmap, NAU8825_REG_CLK_DIVIDER,
NAU8825_CLK_DAC_SRC_MASK,
osr_dac_sel[osr].clk_src << NAU8825_CLK_DAC_SRC_SFT);
@@ -1267,8 +1270,10 @@ static int nau8825_hw_params(struct snd_pcm_substream *substream,
regmap_read(nau8825->regmap, NAU8825_REG_ADC_RATE, &osr);
osr &= NAU8825_ADC_SYNC_DOWN_MASK;
if (nau8825_clock_check(nau8825, substream->stream,
- params_rate(params), osr))
+ params_rate(params), osr)) {
+ nau8825_sema_release(nau8825);
return -EINVAL;
+ }
regmap_update_bits(nau8825->regmap, NAU8825_REG_CLK_DIVIDER,
NAU8825_CLK_ADC_SRC_MASK,
osr_adc_sel[osr].clk_src << NAU8825_CLK_ADC_SRC_SFT);
@@ -1285,8 +1290,10 @@ static int nau8825_hw_params(struct snd_pcm_substream *substream,
bclk_div = 1;
else if (bclk_fs <= 128)
bclk_div = 0;
- else
+ else {
+ nau8825_sema_release(nau8825);
return -EINVAL;
+ }
regmap_update_bits(nau8825->regmap, NAU8825_REG_I2S_PCM_CTRL2,
NAU8825_I2S_LRC_DIV_MASK | NAU8825_I2S_BLK_DIV_MASK,
((bclk_div + 1) << NAU8825_I2S_LRC_DIV_SFT) | bclk_div);
@@ -1306,6 +1313,7 @@ static int nau8825_hw_params(struct snd_pcm_substream *substream,
val_len |= NAU8825_I2S_DL_32;
break;
default:
+ nau8825_sema_release(nau8825);
return -EINVAL;
}
@@ -1324,8 +1332,6 @@ static int nau8825_set_dai_fmt(struct snd_soc_dai *codec_dai, unsigned int fmt)
struct nau8825 *nau8825 = snd_soc_codec_get_drvdata(codec);
unsigned int ctrl1_val = 0, ctrl2_val = 0;
- nau8825_sema_acquire(nau8825, 3 * HZ);
-
switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
case SND_SOC_DAIFMT_CBM_CFM:
ctrl2_val |= NAU8825_I2S_MS_MASTER;
@@ -1367,6 +1373,8 @@ static int nau8825_set_dai_fmt(struct snd_soc_dai *codec_dai, unsigned int fmt)
return -EINVAL;
}
+ nau8825_sema_acquire(nau8825, 3 * HZ);
+
regmap_update_bits(nau8825->regmap, NAU8825_REG_I2S_PCM_CTRL1,
NAU8825_I2S_DL_MASK | NAU8825_I2S_DF_MASK |
NAU8825_I2S_BP_MASK | NAU8825_I2S_PCMB_MASK,
@@ -1713,7 +1721,7 @@ static irqreturn_t nau8825_interrupt(int irq, void *data)
int ret;
nau8825->xtalk_protect = true;
ret = nau8825_sema_acquire(nau8825, 0);
- if (ret < 0)
+ if (ret)
nau8825->xtalk_protect = false;
}
/* Startup cross talk detection process */
@@ -2399,7 +2407,7 @@ static int __maybe_unused nau8825_resume(struct snd_soc_codec *codec)
regcache_sync(nau8825->regmap);
nau8825->xtalk_protect = true;
ret = nau8825_sema_acquire(nau8825, 0);
- if (ret < 0)
+ if (ret)
nau8825->xtalk_protect = false;
enable_irq(nau8825->irq);
After reviewing the crosstalk protection, there are two flaws at semaphore control. The first one is that the semaphore releases are not enough; and the other is that down_interruptible has an risk to make the ISR sleep. Therefore, the driver add more releases before the funcitons return. Take down_trylock to replace down_interruptible. The ISR can control the protection as well and never sleep by semaphore. Signed-off-by: John Hsu <KCHSU0@nuvoton.com> --- sound/soc/codecs/nau8825.c | 38 +++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 15 deletions(-)