Re: [PATCH v2 08/16] iio: adc: sc27xx_adc: do not use internal iio_dev lock

From: Jonathan Cameron <jic23@kernel.org>
To: "Nuno Sá" <nuno.sa@analog.com>
Cc: <linux-amlogic@lists.infradead.org>, <linux-imx@nxp.com>,
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Subject: Re: [PATCH v2 08/16] iio: adc: sc27xx_adc: do not use internal iio_dev lock
Date: Sun, 9 Oct 2022 13:05:14 +0100	[thread overview]
Message-ID: <20221009130514.133eff43@jic23-huawei> (raw)
In-Reply-To: <20221004134909.1692021-9-nuno.sa@analog.com>

On Tue, 4 Oct 2022 15:49:01 +0200
Nuno Sá <nuno.sa@analog.com> wrote:

> The iio_device lock is only meant for internal use. Hence define a
> device local lock to protect against concurrent accesses.
> 
> While at it, properly include "mutex.h" for mutex related APIs.
> 
> Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Applied. Pushed out as testing for now, will rebase after rc1.

Thanks,

J
> ---
>  drivers/iio/adc/sc27xx_adc.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/sc27xx_adc.c b/drivers/iio/adc/sc27xx_adc.c
> index f8421cbba8fa..ff1fc329bb9b 100644
> --- a/drivers/iio/adc/sc27xx_adc.c
> +++ b/drivers/iio/adc/sc27xx_adc.c
> @@ -4,6 +4,7 @@
>  #include <linux/hwspinlock.h>
>  #include <linux/iio/iio.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/nvmem-consumer.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> @@ -83,6 +84,8 @@ struct sc27xx_adc_data {
>  	struct device *dev;
>  	struct regulator *volref;
>  	struct regmap *regmap;
> +	/* lock to protect against multiple access to the device */
> +	struct mutex lock;
>  	/*
>  	 * One hardware spinlock to synchronize between the multiple
>  	 * subsystems which will access the unique ADC controller.
> @@ -664,9 +667,9 @@ static int sc27xx_adc_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&data->lock);
>  		ret = sc27xx_adc_read(data, chan->channel, scale, &tmp);
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&data->lock);
>  
>  		if (ret)
>  			return ret;
> @@ -675,10 +678,10 @@ static int sc27xx_adc_read_raw(struct iio_dev *indio_dev,
>  		return IIO_VAL_INT;
>  
>  	case IIO_CHAN_INFO_PROCESSED:
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&data->lock);
>  		ret = sc27xx_adc_read_processed(data, chan->channel, scale,
>  						&tmp);
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&data->lock);
>  
>  		if (ret)
>  			return ret;
> @@ -934,6 +937,9 @@ static int sc27xx_adc_probe(struct platform_device *pdev)
>  	indio_dev->info = &sc27xx_info;
>  	indio_dev->channels = sc27xx_channels;
>  	indio_dev->num_channels = ARRAY_SIZE(sc27xx_channels);
> +
> +	mutex_init(&sc27xx_data->lock);
> +
>  	ret = devm_iio_device_register(dev, indio_dev);
>  	if (ret)
>  		dev_err(dev, "could not register iio (ADC)");


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