Commit 2544ea7b authored by Sergiu Cuciurean's avatar Sergiu Cuciurean Committed by Jonathan Cameron
Browse files

iio: stm32-dac: Replace indio_dev->mlock with own device lock 

As part of the general cleanup of indio_dev->mlock, this change replaces
it with a local lock. The lock protects against potential races when
reading the CR reg and then updating, so that the state of pm_runtime
is consistent between the two operations.

This is part of a bigger cleanup.
Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/



Signed-off-by: default avatarSergiu Cuciurean <sergiu.cuciurean@analog.com>
Signed-off-by: default avatarAlexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: default avatarFabrice Gasnier <fabrice.gasnier@st.com>
Link: https://lore.kernel.org/r/20200916092349.75647-1-alexandru.ardelean@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent d3e0e14d

drivers/iio/dac/stm32-dac.c

+9 −4
Original line number Diff line number Diff line
@@ -26,9 +26,12 @@ 
/**

 * struct stm32_dac - private data of DAC driver

 * @common:		reference to DAC common data

 * @lock:		lock to protect against potential races when reading

 *			and update CR, to keep it in sync with pm_runtime

 */

struct stm32_dac {

	struct stm32_dac_common *common;

	struct mutex		lock;

};



static int stm32_dac_is_enabled(struct iio_dev *indio_dev, int channel)
@@ -58,10 +61,10 @@ static int stm32_dac_set_enable_state(struct iio_dev *indio_dev, int ch, 
	int ret;



	/* already enabled / disabled ? */

	mutex_lock(&indio_dev->mlock);

	mutex_lock(&dac->lock);

	ret = stm32_dac_is_enabled(indio_dev, ch);

	if (ret < 0 || enable == !!ret) {

		mutex_unlock(&indio_dev->mlock);

		mutex_unlock(&dac->lock);

		return ret < 0 ? ret : 0;

	}
@@ -69,13 +72,13 @@ static int stm32_dac_set_enable_state(struct iio_dev *indio_dev, int ch, 
		ret = pm_runtime_get_sync(dev);

		if (ret < 0) {

			pm_runtime_put_noidle(dev);

			mutex_unlock(&indio_dev->mlock);

			mutex_unlock(&dac->lock);

			return ret;

		}

	}



	ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, msk, en);

	mutex_unlock(&indio_dev->mlock);

	mutex_unlock(&dac->lock);

	if (ret < 0) {

		dev_err(&indio_dev->dev, "%s failed\n", en ?

			"Enable" : "Disable");
@@ -327,6 +330,8 @@ static int stm32_dac_probe(struct platform_device *pdev) 
	indio_dev->info = &stm32_dac_iio_info;

	indio_dev->modes = INDIO_DIRECT_MODE;



	mutex_init(&dac->lock);



	ret = stm32_dac_chan_of_init(indio_dev);

	if (ret < 0)

		return ret;