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Unverified Commit 70424d8e authored by John Hsu's avatar John Hsu Committed by Mark Brown
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ASoC: nau8825: improve semaphore control 



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: default avatarJohn Hsu <KCHSU0@nuvoton.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent e3fee43a

sound/soc/codecs/nau8825.c

+23 −15
Original line number Diff line number Diff line
@@ -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");

	}
@@ -1246,8 +1247,10 @@ 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);
@@ -1255,8 +1258,10 @@ 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);
@@ -1273,8 +1278,10 @@ 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);
@@ -1294,6 +1301,7 @@ static int nau8825_hw_params(struct snd_pcm_substream *substream, 
		val_len |= NAU8825_I2S_DL_32;

		break;

	default:

		nau8825_sema_release(nau8825);

		return -EINVAL;

	}
@@ -1312,8 +1320,6 @@ 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;
@@ -1355,6 +1361,8 @@ 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,
@@ -1701,7 +1709,7 @@ 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 */
@@ -2383,7 +2391,7 @@ 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);