linux-kernel - Re: [PATCH] Removing ununsed variable int lo, hi, int data and int i from comedi/drivers/dt2814.c.

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Date:   Sun, 24 May 2020 14:10:44 +0200
From:   Luc Van Oostenryck <luc.vanoostenryck@...il.com>
To:     Gaurav Pathak <gauravpathak129@...il.com>
Cc:     abbotti@....co.uk, gregkh@...uxfoundation.org,
        hsweeten@...ionengravers.com, linux-kernel@...r.kernel.org,
        devel@...verdev.osuosl.org
Subject: Re: [PATCH] Removing ununsed variable int lo, hi, int data and int i
 from comedi/drivers/dt2814.c.

Hi,

On Sun, May 24, 2020 at 05:06:18PM +0530, Gaurav Pathak wrote:
> Silence following sparse warning:
> drivers/staging/comedi/drivers/dt2814.c: In function ‘dt2814_interrupt’:
> drivers/staging/comedi/drivers/dt2814.c:193:6: warning: variable ‘data’ set but not used [-Wunused-but-set-variable]
>   int data;
>       ^~~~
> drivers/staging/comedi/drivers/dt2814.c: In function ‘dt2814_attach’:
> drivers/staging/comedi/drivers/dt2814.c:232:6: warning: variable ‘i’ set but not used [-Wunused-but-set-variable]
>   int i;
>       ^

These warnings are not from sparse but simply from the compiler.
 
>  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);

OK, 'data' is unused but are these 2 'inb(dev->iobase + DT2814_DATA)'
needed or not? I would guess that they're needed but I don't know
this hardware.

> @@ -241,8 +233,6 @@ 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);

Same here.

-- Luc