linux-kernel - Re: [PATCH 06/15] iio: ti_am335x_adc: Handle set to clear IRQENABLE

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Date:	Sat, 20 Jul 2013 12:19:43 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Zubair Lutfullah <zubair.lutfullah@...il.com>
CC:	jic23@....ac.uk, gregkh@...uxfoundation.org,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	koen@...inion.thruhere.net
Subject: Re: [PATCH 06/15] iio: ti_am335x_adc: Handle set to clear IRQENABLE

On 07/18/2013 11:21 PM, Zubair Lutfullah wrote:
> From: Russ Dill <Russ.Dill@...com>
> 
> The driver is currently mishandling the IRQENABLE register. The driver
> should write a 1 for bits it wishes to set, and a zero for bits it does not
> wish to change. The read of the current register contents is not
> necessary.
> 
> Write 0 = No action.
> Read 0 = Interrupt disabled (masked).
> Read 1 = Interrupt enabled.
> Write 1 = Enable interrupt.
> 
> The current read/update/write method is currently not causing any
> problems, but could cause confusion in the future.
> 
> Signed-off-by: Russ Dill <Russ.Dill@...com>
> Signed-off-by: Zubair Lutfullah <zubair.lutfullah@...il.com>

I guess this makes sense as a separate patch to maintain history, but
I'd personally have preferred it rolled into the write places and
appropriate credit given as comments.

I don't like the fact that the code will be broken in a known fashion
at somepoints in this series...

Jonathan
> ---
>  drivers/iio/adc/ti_am335x_adc.c |   14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
> index c1b051c..b566e6a 100644
> --- a/drivers/iio/adc/ti_am335x_adc.c
> +++ b/drivers/iio/adc/ti_am335x_adc.c
> @@ -207,7 +207,7 @@ static void tiadc_poll_handler(struct work_struct *work_s)
>  		container_of(work_s, struct tiadc_device, poll_work);
>  	struct iio_dev *idev = iio_priv_to_dev(adc_dev);
>  	struct iio_buffer *buffer = idev->buffer;
> -	unsigned int fifo1count, readx1, status;
> +	unsigned int fifo1count, readx1;
>  	int i;
>  	u32 *inputbuffer;
>  
> @@ -223,9 +223,8 @@ static void tiadc_poll_handler(struct work_struct *work_s)
>  	}
>  
>  	buffer->access->store_to(buffer, (u8 *) inputbuffer);
> -	status = tiadc_readl(adc_dev, REG_IRQENABLE);
>  	tiadc_writel(adc_dev, REG_IRQENABLE,
> -			(status | IRQENB_FIFO1THRES));
> +			IRQENB_FIFO1THRES);
>  
>  	kfree(inputbuffer);
>  }
> @@ -242,7 +241,7 @@ static int tiadc_buffer_postenable(struct iio_dev *idev)
>  {
>  	struct tiadc_device *adc_dev = iio_priv(idev);
>  	struct iio_buffer *buffer = idev->buffer;
> -	unsigned int enb, status, fifo1count;
> +	unsigned int enb, fifo1count;
>  	int stepnum, i;
>  	u8 bit;
>  
> @@ -250,11 +249,10 @@ static int tiadc_buffer_postenable(struct iio_dev *idev)
>  		pr_info("Data cannot be read continuously in one shot mode\n");
>  		return -EINVAL;
>  	} else {
> -		status = tiadc_readl(adc_dev, REG_IRQENABLE);
>  		tiadc_writel(adc_dev, REG_IRQENABLE,
> -				(status | IRQENB_FIFO1THRES)|
> -				 IRQENB_FIFO1OVRRUN |
> -				 IRQENB_FIFO1UNDRFLW);
> +				(IRQENB_FIFO1THRES |
> +				IRQENB_FIFO1OVRRUN |
> +				IRQENB_FIFO1UNDRFLW));
>  
>  		fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
>  		for (i = 0; i < fifo1count; i++)
> 
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