linux-kernel - Re: [PATCH 3/6] staging: comedi: usbduxsigma: remove AI scan_begin_src == TRIG

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Message-ID: <55B26EC8.6090703@berndporr.me.uk>
Date:	Fri, 24 Jul 2015 17:58:48 +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 3/6] staging: comedi: usbduxsigma: remove AI scan_begin_src
 == TRIG_FOLLOW

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

Ian Abbott wrote:
> The AI subdevice `cmdtest` handler `usbduxsigma_ai_cmdtest()` ensures
> that `cmd->scan_begin_src == TRIG_TIMER` by the end of step 2 of the
> command checking code, so assume that this is the case for step 3
> onwards and remove the redundant code.
> 
> Signed-off-by: Ian Abbott <abbotti@....co.uk>
> ---
>  drivers/staging/comedi/drivers/usbduxsigma.c | 47 +++++++++++-----------------
>  1 file changed, 19 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
> index dc0b25a..65a0df4 100644
> --- a/drivers/staging/comedi/drivers/usbduxsigma.c
> +++ b/drivers/staging/comedi/drivers/usbduxsigma.c
> @@ -481,6 +481,7 @@ static int usbduxsigma_ai_cmdtest(struct comedi_device *dev,
>  	struct usbduxsigma_private *devpriv = dev->private;
>  	int high_speed = devpriv->high_speed;
>  	int interval = usbduxsigma_chans_to_interval(cmd->chanlist_len);
> +	unsigned int tmp;
>  	int err = 0;
>  
>  	/* Step 1 : check if triggers are trivially valid */
> @@ -508,36 +509,26 @@ static int usbduxsigma_ai_cmdtest(struct comedi_device *dev,
>  
>  	err |= comedi_check_trigger_arg_is(&cmd->start_arg, 0);
>  
> -	if (cmd->scan_begin_src == TRIG_FOLLOW)	/* internal trigger */
> -		err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, 0);
> +	if (high_speed) {
> +		/*
> +		 * In high speed mode microframes are possible.
> +		 * However, during one microframe we can roughly
> +		 * sample two channels. Thus, the more channels
> +		 * are in the channel list the more time we need.
> +		 */
> +		err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
> +						    (125000 * interval));
>  
> -	if (cmd->scan_begin_src == TRIG_TIMER) {
> -		unsigned int tmp;
> -
> -		if (high_speed) {
> -			/*
> -			 * In high speed mode microframes are possible.
> -			 * However, during one microframe we can roughly
> -			 * sample two channels. Thus, the more channels
> -			 * are in the channel list the more time we need.
> -			 */
> -			err |= comedi_check_trigger_arg_min(&cmd->
> -							    scan_begin_arg,
> -							    (1000000 / 8 *
> -							     interval));
> -
> -			tmp = (cmd->scan_begin_arg / 125000) * 125000;
> -		} else {
> -			/* full speed */
> -			/* 1kHz scans every USB frame */
> -			err |= comedi_check_trigger_arg_min(&cmd->
> -							    scan_begin_arg,
> -							    1000000);
> -
> -			tmp = (cmd->scan_begin_arg / 1000000) * 1000000;
> -		}
> -		err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, tmp);
> +		tmp = (cmd->scan_begin_arg / 125000) * 125000;
> +	} else {
> +		/* full speed */
> +		/* 1kHz scans every USB frame */
> +		err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
> +						    1000000);
> +
> +		tmp = (cmd->scan_begin_arg / 1000000) * 1000000;
>  	}
> +	err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, tmp);
>  
>  	err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg,
>  					   cmd->chanlist_len);

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