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

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Date:	Thu, 23 Jul 2015 16:47:02 +0100
From:	Ian Abbott <abbotti@....co.uk>
To:	<driverdev-devel@...uxdriverproject.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ian Abbott <abbotti@....co.uk>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>,
	Bernd Porr <mail@...ndporr.me.uk>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH 6/6] staging: comedi: usbduxsigma: round down AO scan_begin_arg at step 4.

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;
 }
 
-- 
2.1.4

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