Re: [PATCH v3] iio: exynos_adc: use wait_for_completion_timeout instead of interruptible

[Lars-Peter Clausen <lars@metafoo.de>]

On 10/11/2013 10:23 AM, Naveen Krishna Chatradhi wrote:
> This patch does the following
> 1. use wait_for_completion_timeout instead of
>    wait_for_completion_interruptible_timeout
> 2. Reset software if a timeout happens.
> 3. Also reduce the timeout to 100milli secs

It is always good to have a description of why a chance should be done in
the commit message. It is obvious what the patch does by just looking at the
changed lines, it is not that obvious though why those lines had to be changed.

> 
> Note: submitted for review at https://patchwork.kernel.org/patch/2279591/
> 
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
> Cc: Doug Anderson <dianders@chromium.org>
> Cc: Lars-Peter Clausen <lars@metafoo.de>
> ---
> Changes since v1:
> As per discussion at
> http://marc.info/?l=linux-kernel&m=136517637228869&w=3
> 
> This patch does the following
> 1. use wait_for_completion_timeout instead of
>    wait_for_completion_interruptible_timeout
> 2. Reset software if a timeout happens.
> 3. Also reduce the timeout to 100milli secs
> 
> Changes since v2:
> None.
> Rebased and reposting.
> 
> ---
>  drivers/iio/adc/exynos_adc.c |   66 +++++++++++++++++++++++-------------------
>  1 file changed, 36 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
> index d25b262..f18ed7e 100644
> --- a/drivers/iio/adc/exynos_adc.c
> +++ b/drivers/iio/adc/exynos_adc.c
> @@ -82,7 +82,7 @@ enum adc_version {
>  #define ADC_CON_EN_START	(1u << 0)
>  #define ADC_DATX_MASK		0xFFF
>  
> -#define EXYNOS_ADC_TIMEOUT	(msecs_to_jiffies(1000))
> +#define EXYNOS_ADC_TIMEOUT	(msecs_to_jiffies(100))
>  
>  struct exynos_adc {
>  	void __iomem		*regs;
> @@ -112,6 +112,30 @@ static inline unsigned int exynos_adc_get_version(struct platform_device *pdev)
>  	return (unsigned int)match->data;
>  }
>  
> +static void exynos_adc_hw_init(struct exynos_adc *info)
> +{
> +	u32 con1, con2;
> +
> +	if (info->version == ADC_V2) {
> +		con1 = ADC_V2_CON1_SOFT_RESET;
> +		writel(con1, ADC_V2_CON1(info->regs));
> +
> +		con2 = ADC_V2_CON2_OSEL | ADC_V2_CON2_ESEL |
> +			ADC_V2_CON2_HIGHF | ADC_V2_CON2_C_TIME(0);
> +		writel(con2, ADC_V2_CON2(info->regs));
> +
> +		/* Enable interrupts */
> +		writel(1, ADC_V2_INT_EN(info->regs));
> +	} else {
> +		/* set default prescaler values and Enable prescaler */
> +		con1 =  ADC_V1_CON_PRSCLV(49) | ADC_V1_CON_PRSCEN;
> +
> +		/* Enable 12-bit ADC resolution */
> +		con1 |= ADC_V1_CON_RES;
> +		writel(con1, ADC_V1_CON(info->regs));
> +	}
> +}
> +
>  static int exynos_read_raw(struct iio_dev *indio_dev,
>  				struct iio_chan_spec const *chan,
>  				int *val,
> @@ -121,6 +145,7 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
>  	struct exynos_adc *info = iio_priv(indio_dev);
>  	unsigned long timeout;
>  	u32 con1, con2;
> +	int ret;
>  
>  	if (mask != IIO_CHAN_INFO_RAW)
>  		return -EINVAL;
> @@ -145,16 +170,21 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
>  				ADC_V1_CON(info->regs));
>  	}
>  
> -	timeout = wait_for_completion_interruptible_timeout
> +	timeout = wait_for_completion_timeout
>  			(&info->completion, EXYNOS_ADC_TIMEOUT);

Nitpick: It would be nice to put the &info->completion on the same line as
the wait_for_completion...

> +	if (timeout == 0) {
> +		dev_warn(&indio_dev->dev, "Conversion timed out reseting\n");
> +		exynos_adc_hw_init(info);
> +		ret = -ETIMEDOUT;
> +	} else {
> +		*val = info->value;
> +		ret = IIO_VAL_INT;
> +	}
>  	*val = info->value;

This line above should probably be removed.

>  
>  	mutex_unlock(&indio_dev->mlock);
>  
> -	if (timeout == 0)
> -		return -ETIMEDOUT;
> -
> -	return IIO_VAL_INT;
> +	return ret;
>  }
>  
>  static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
> @@ -226,30 +256,6 @@ static int exynos_adc_remove_devices(struct device *dev, void *c)
>  	return 0;
>  }
>  
> -static void exynos_adc_hw_init(struct exynos_adc *info)
> -{
> -	u32 con1, con2;
> -
> -	if (info->version == ADC_V2) {
> -		con1 = ADC_V2_CON1_SOFT_RESET;
> -		writel(con1, ADC_V2_CON1(info->regs));
> -
> -		con2 = ADC_V2_CON2_OSEL | ADC_V2_CON2_ESEL |
> -			ADC_V2_CON2_HIGHF | ADC_V2_CON2_C_TIME(0);
> -		writel(con2, ADC_V2_CON2(info->regs));
> -
> -		/* Enable interrupts */
> -		writel(1, ADC_V2_INT_EN(info->regs));
> -	} else {
> -		/* set default prescaler values and Enable prescaler */
> -		con1 =  ADC_V1_CON_PRSCLV(49) | ADC_V1_CON_PRSCEN;
> -
> -		/* Enable 12-bit ADC resolution */
> -		con1 |= ADC_V1_CON_RES;
> -		writel(con1, ADC_V1_CON(info->regs));
> -	}
> -}
> -
>  static int exynos_adc_probe(struct platform_device *pdev)
>  {
>  	struct exynos_adc *info = NULL;
>