The value read from the encoders is in two's complement format. Use
the comedi_offset_munge() helper to convert the value to offset binary.
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/c6xdigio.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/comedi/drivers/c6xdigio.c
b/drivers/staging/comedi/drivers/c6xdigio.c
index 3937e64..20a5dfe 100644
--- a/drivers/staging/comedi/drivers/c6xdigio.c
+++ b/drivers/staging/comedi/drivers/c6xdigio.c
@@ -153,7 +153,7 @@ static int c6xdigio_encoder_read(struct comedi_device *dev,
c6xdigio_write_data(dev, 0x00, 0x80);
- return val ^ 0x800000;
+ return val;
}
static int c6xdigio_pwm_insn_write(struct comedi_device *dev,
@@ -177,12 +177,17 @@ static int c6xdigio_encoder_insn_read(struct
comedi_device *dev,
unsigned int *data)
{
unsigned int chan = CR_CHAN(insn->chanspec);
- int n;
+ unsigned int val;
+ int i;
- for (n = 0; n < insn->n; n++)
- data[n] = (c6xdigio_encoder_read(dev, chan) & 0xffffff);
+ for (i = 0; i < insn->n; i++) {
+ val = c6xdigio_encoder_read(dev, chan);
+
+ /* munge two's complement value to offset binary */
+ data[i] = comedi_offset_munge(s, val);
+ }
- return n;
+ return insn->n;
}
static void c6xdigio_init(struct comedi_device *dev)
--
1.8.5.2
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