[PATCH 14/18] staging: comedi: usbdux: use comedi_async 'scans_done' to detect AI EOA

[Ian Abbott]

On 04/11/14 16:50, H Hartley Sweeten wrote:
> Remove the private data member 'ai_sample_count' and use the comedi_async
> 'scans_done' member to detect the analog input end-of-acquisition.
>
> Move the EOA check so it happens after adding the samples from the current
> urb to the async buffer. This prevents the unnecessary resubmit of the urb
> when the EOA occurs.
>
> Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
> Cc: Ian Abbott <abbotti at mev.co.uk>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> ---
>   drivers/staging/comedi/drivers/usbdux.c | 22 ++++------------------
>   1 file changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/usbdux.c b/drivers/staging/comedi/drivers/usbdux.c
> index 7782015..4737dbf 100644
> --- a/drivers/staging/comedi/drivers/usbdux.c
> +++ b/drivers/staging/comedi/drivers/usbdux.c
> @@ -202,8 +202,6 @@ struct usbdux_private {
>   	unsigned int ao_cmd_running:1;
>   	unsigned int pwm_cmd_running:1;
>
> -	/* number of samples to acquire */
> -	int ai_sample_count;
>   	/* time between samples in units of the timer */
>   	unsigned int ai_timer;
>   	unsigned int ao_timer;
> @@ -263,14 +261,6 @@ static void usbduxsub_ai_handle_urb(struct comedi_device *dev,
>   	if (devpriv->ai_counter == 0) {
>   		devpriv->ai_counter = devpriv->ai_timer;
>
> -		if (cmd->stop_src == TRIG_COUNT) {
> -			devpriv->ai_sample_count--;
> -			if (devpriv->ai_sample_count < 0) {
> -				async->events |= COMEDI_CB_EOA;
> -				return;
> -			}
> -		}
> -
>   		/* get the data from the USB bus and hand it over to comedi */
>   		for (i = 0; i < cmd->chanlist_len; i++) {
>   			unsigned int range = CR_RANGE(cmd->chanlist[i]);
> @@ -284,6 +274,10 @@ static void usbduxsub_ai_handle_urb(struct comedi_device *dev,
>   			if (!comedi_buf_write_samples(s, &val, 1))
>   				return;
>   		}
> +
> +		if (cmd->stop_src == TRIG_COUNT &&
> +		    async->scans_done >= cmd->stop_arg)
> +			async->events |= COMEDI_CB_EOA;

You could return early here, but it doesn't really matter as the 
following code does nothing if COMEDI_CB_EOA is set.

>   	}
>
>   	/* if command is still running, resubmit urb */
> @@ -732,14 +726,6 @@ static int usbdux_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
>
>   	devpriv->ai_counter = devpriv->ai_timer;
>
> -	if (cmd->stop_src == TRIG_COUNT) {
> -		/* data arrives as one packet */
> -		devpriv->ai_sample_count = cmd->stop_arg;
> -	} else {
> -		/* continous acquisition */
> -		devpriv->ai_sample_count = 0;
> -	}
> -
>   	if (cmd->start_src == TRIG_NOW) {
>   		/* enable this acquisition operation */
>   		devpriv->ai_cmd_running = 1;
>


-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti at mev.co.uk> )=-
-=(                          Web: http://www.mev.co.uk/  )=-