linux-kernel - Re: [PATCH -next] staging: comedi dt2814: Removed unused variables

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Date:   Mon, 22 Feb 2021 10:45:57 +0000
From:   Ian Abbott <abbotti@....co.uk>
To:     Fatih Yildirim <yildirim.fatih@...il.com>,
        hsweeten@...ionengravers.com, gregkh@...uxfoundation.org,
        grandmaster@...klimov.de
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] staging: comedi dt2814: Removed unused variables

On 21/02/2021 20:28, Fatih Yildirim wrote:
> Removed unused variables.
> 
> Signed-off-by: Fatih Yildirim <yildirim.fatih@...il.com>
> ---
>  drivers/staging/comedi/drivers/dt2814.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/staging/comedi/drivers/dt2814.c b/drivers/staging/comedi/drivers/dt2814.c
> index bcf4d5444faf..bd329d7b4893 100644
> --- a/drivers/staging/comedi/drivers/dt2814.c
> +++ b/drivers/staging/comedi/drivers/dt2814.c
> @@ -186,21 +186,17 @@ static int dt2814_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
>  
>  static irqreturn_t dt2814_interrupt(int irq, void *d)
>  {
> -	int lo, hi;
>  	struct comedi_device *dev = d;
>  	struct dt2814_private *devpriv = dev->private;
>  	struct comedi_subdevice *s = dev->read_subdev;
> -	int data;
>  
>  	if (!dev->attached) {
>  		dev_err(dev->class_dev, "spurious interrupt\n");
>  		return IRQ_HANDLED;
>  	}
>  
> -	hi = inb(dev->iobase + DT2814_DATA);
> -	lo = inb(dev->iobase + DT2814_DATA);
> -
> -	data = (hi << 4) | (lo >> 4);
> +	inb(dev->iobase + DT2814_DATA);
> +	inb(dev->iobase + DT2814_DATA);
>  
>  	if (!(--devpriv->ntrig)) {
>  		int i;
> @@ -229,7 +225,6 @@ static int dt2814_attach(struct comedi_device *dev, struct comedi_devconfig *it)
>  	struct dt2814_private *devpriv;
>  	struct comedi_subdevice *s;
>  	int ret;
> -	int i;
>  
>  	ret = comedi_request_region(dev, it->options[0], 0x2);
>  	if (ret)
> @@ -241,8 +236,8 @@ static int dt2814_attach(struct comedi_device *dev, struct comedi_devconfig *it)
>  		dev_err(dev->class_dev, "reset error (fatal)\n");
>  		return -EIO;
>  	}
> -	i = inb(dev->iobase + DT2814_DATA);
> -	i = inb(dev->iobase + DT2814_DATA);
> +	inb(dev->iobase + DT2814_DATA);
> +	inb(dev->iobase + DT2814_DATA);
>  
>  	if (it->options[1]) {
>  		ret = request_irq(it->options[1], dt2814_interrupt, 0,
> 

I've no objection to this patch.  The interrupt handling to support
Comedi asynchronous commands in this driver has always been broken.  I'm
tempted to remove the code for handling asynchronous commands in this
driver altogether for that reason.  (The naive fix of writing the data
to the Comedi buffer is insufficient without an additional check that
the command is running.  The end-of-conversion interrupt occurs
regardless of any command being active.)

Acked-by: Ian Abbott <abbotti@....co.uk>

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