According the the PCI-2006M user's manual, bipolar ranges use 2's
complement coding and unipolar ranges are straight binary. Fix
ii20k_ao_insn_write() to use the correct coding based on the range.
For aesthetics, use the comedi_offset_munge() helper to handle the
munging of the data.
Signed-off-by: H Hartley Sweeten <hswee...@visionengravers.com>
Cc: Ian Abbott <abbo...@mev.co.uk>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/staging/comedi/drivers/ii_pci20kc.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ii_pci20kc.c
b/drivers/staging/comedi/drivers/ii_pci20kc.c
index 4d3f89c..6e2ce93 100644
--- a/drivers/staging/comedi/drivers/ii_pci20kc.c
+++ b/drivers/staging/comedi/drivers/ii_pci20kc.c
@@ -146,6 +146,7 @@ static int ii20k_ao_insn_write(struct comedi_device *dev,
{
void __iomem *iobase = ii20k_module_iobase(dev, s);
unsigned int chan = CR_CHAN(insn->chanspec);
+ unsigned int range = CR_RANGE(insn->chanspec);
int i;
for (i = 0; i < insn->n; i++) {
@@ -153,9 +154,9 @@ static int ii20k_ao_insn_write(struct comedi_device *dev,
s->readback[chan] = val;
- /* munge data */
- val += ((s->maxdata + 1) >> 1);
- val &= s->maxdata;
+ /* munge the offset binary to 2's complement if needed */
+ if (comedi_range_is_bipolar(s, range))
+ val = comedi_offset_munge(s, val);
writeb(val & 0xff, iobase + II20K_AO_LSB_REG(chan));
writeb((val >> 8) & 0xff, iobase + II20K_AO_MSB_REG(chan));
--
2.5.1
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