[PATCH 03/19] staging: comedi: cb_pcidas64: fix calib_write_insn()

[H Hartley Sweeten]

The comedi core expects the (*insn_write) functions to write 'insn->n'
values to the hardware and return the number of values written. Currently
this function only writes the first value. For this subdevice it only makes
sense to write the final data value.

Fix the function to work like the core expects. For aesthetics, rename the
function so it has namespace associated with the driver.

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/cb_pcidas64.c | 30 +++++++++++++++++-----------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/comedi/drivers/cb_pcidas64.c b/drivers/staging/comedi/drivers/cb_pcidas64.c
index c641778..17c98a5 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas64.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
@@ -3563,21 +3563,27 @@ static void caldac_write(struct comedi_device *dev, unsigned int channel,
 	}
 }
 
-static int calib_write_insn(struct comedi_device *dev,
-			    struct comedi_subdevice *s,
-			    struct comedi_insn *insn, unsigned int *data)
+static int cb_pcidas64_calib_insn_write(struct comedi_device *dev,
+					struct comedi_subdevice *s,
+					struct comedi_insn *insn,
+					unsigned int *data)
 {
-	int channel = CR_CHAN(insn->chanspec);
+	unsigned int chan = CR_CHAN(insn->chanspec);
 
-	/* return immediately if setting hasn't changed, since
-	 * programming these things is slow */
-	if (s->readback[channel] == data[0])
-		return 1;
+	/*
+	 * Programming the calib device is slow. Only write the
+	 * last data value if the value has changed.
+	 */
+	if (insn->n) {
+		unsigned int val = data[insn->n - 1];
 
-	caldac_write(dev, channel, data[0]);
-	s->readback[channel] = data[0];
+		if (s->readback[chan] != val) {
+			caldac_write(dev, chan, val);
+			s->readback[chan] = val;
+		}
+	}
 
-	return 1;
+	return insn->n;
 }
 
 static void ad8402_write(struct comedi_device *dev, unsigned int channel,
@@ -3848,7 +3854,7 @@ static int setup_subdevices(struct comedi_device *dev)
 		s->maxdata = 0xfff;
 	else
 		s->maxdata = 0xff;
-	s->insn_write = calib_write_insn;
+	s->insn_write = cb_pcidas64_calib_insn_write;
 
 	ret = comedi_alloc_subdev_readback(s);
 	if (ret)
-- 
2.0.3