linux-kernel - Re: [PATCH 6/6] staging: comedi: usbduxsigma: round down AO scan_begin

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Message-ID: <55B26EE2.6080005@berndporr.me.uk>
Date:	Fri, 24 Jul 2015 17:59:14 +0100
From:	Bernd Porr <mail@...ndporr.me.uk>
To:	Ian Abbott <abbotti@....co.uk>
CC:	driverdev-devel@...uxdriverproject.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] staging: comedi: usbduxsigma: round down AO scan_begin_arg
 at step 4.

Reviewed-by: Bernd Porr <mail@...ndporr.me.uk>

Ian Abbott wrote:
> The return value of the `cmdtest` handler for a subdevice checks the
> prospective new command in various steps and returns the step number at
> which any problem was detected, or 0 if no problem was detected.  It is
> allowed to modify the command in various ways at each step.  Corrections
> for out-of-range values are generally made at step 3, and minor
> adjustments such as rounding are generally made at step 4.
> 
> The `cmdtest` handler for the AO subdevice (`usbduxsigma_ao_cmdtest()`)
> currently range checks the timings at step 3.  Since the running command
> will round down the timings, add code to round them down at step 4.
> 
> Signed-off-by: Ian Abbott <abbotti@....co.uk>
> ---
>  drivers/staging/comedi/drivers/usbduxsigma.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
> index d97253e..e22c374 100644
> --- a/drivers/staging/comedi/drivers/usbduxsigma.c
> +++ b/drivers/staging/comedi/drivers/usbduxsigma.c
> @@ -837,6 +837,7 @@ static int usbduxsigma_ao_cmdtest(struct comedi_device *dev,
>  				  struct comedi_cmd *cmd)
>  {
>  	struct usbduxsigma_private *devpriv = dev->private;
> +	unsigned int tmp;
>  	int err = 0;
>  
>  	/* Step 1 : check if triggers are trivially valid */
> @@ -888,6 +889,14 @@ static int usbduxsigma_ao_cmdtest(struct comedi_device *dev,
>  	if (err)
>  		return 3;
>  
> +	/* Step 4: fix up any arguments */
> +
> +	tmp = rounddown(cmd->scan_begin_arg, 1000000);
> +	err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, tmp);
> +
> +	if (err)
> +		return 4;
> +
>  	return 0;
>  }
>  

-- 
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