Re: [PATCH -next] staging: comedi: dyna_pci10xx: remove set but not used variables 'chan' and range'

[Ian Abbott]

On 06/04/2019 04:07, YueHaibing wrote:
> Fixes gcc '-Wunused-but-set-variable' warning:
>
> drivers/staging/comedi/drivers/dyna_pci10xx.c: In function 'dyna_pci10xx_insn_write_ao':
> drivers/staging/comedi/drivers/dyna_pci10xx.c:109:21: warning:
>   variable 'range' set but not used [-Wunused-but-set-variable]
>    unsigned int chan, range;
>
> drivers/staging/comedi/drivers/dyna_pci10xx.c:109:15: warning:
>   variable 'chan' set but not used [-Wunused-but-set-variable]
>    unsigned int chan, range;
>
> They are never used since introduction in commit 16a7373a8e14 ("Staging:
> comedi: add dyna_pci10xx driver")
>
> Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
> ---
>   drivers/staging/comedi/drivers/dyna_pci10xx.c | 4 ----
>   1 file changed, 4 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/dyna_pci10xx.c b/drivers/staging/comedi/drivers/dyna_pci10xx.c
> index 9bdd5bf2eb99..d38bfc6113e8 100644
> --- a/drivers/staging/comedi/drivers/dyna_pci10xx.c
> +++ b/drivers/staging/comedi/drivers/dyna_pci10xx.c
> @@ -106,10 +106,6 @@ static int dyna_pci10xx_insn_write_ao(struct comedi_device *dev,
>   {
>   	struct dyna_pci10xx_private *devpriv = dev->private;
>   	int n;
> -	unsigned int chan, range;
> -
> -	chan = CR_CHAN(insn->chanspec);
> -	range = range_codes_pci1050_ai[CR_RANGE((insn->chanspec))];
>   
>   	mutex_lock(&devpriv->mutex);
>   	for (n = 0; n < insn->n; n++) {

That seems fine, thanks.  The lines being removed appear to have been 
copy and pasted from dyna_pci10xx_insn_read_ai().  The AO subdevice 
supports a single range, so no 'range' code is needed.  I believe the 
card has only one analog output channel[*], so the 'chan' is irrelevant. 
 This means the 'n_chans' value in the AO subdevice configuration is 
incorrect.  I'll send a follow-up patch to correct that after Greg KH 
takes this one.

[*] Very little information seems to be available about this card 
online.  It is no longer listed on the manufacturer's web-site and I 
couldn't find any archives on archive.org.  I found part of a scientific 
paper
<http://shodhganga.inflibnet.ac.in/bitstream/10603/150646/15/15_chapter%205.pdf>
which describes the card as having a single channel D/A converter.

Reviewed-by: Ian Abbott <abbotti@xxxxxxxxx>

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