The 'board' pointer is only used in this function to verify that the
'chan' is valid for an aref of AREF_DIFF. For differential inputs, the
maximum channel is half the subdevice 'n_chan'. Use that instead and
remove the 'board' variable.
Also, the comedi core does not validate the aref flags. Add a check
to ensure that the subdevice actually supports the AREF_DIFF mode.
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/me4000.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/comedi/drivers/me4000.c
b/drivers/staging/comedi/drivers/me4000.c
index d6b7adc..335fafc 100644
--- a/drivers/staging/comedi/drivers/me4000.c
+++ b/drivers/staging/comedi/drivers/me4000.c
@@ -436,10 +436,10 @@ static void me4000_reset(struct comedi_device *dev)
===========================================================================*/
static int me4000_ai_insn_read(struct comedi_device *dev,
- struct comedi_subdevice *subdevice,
- struct comedi_insn *insn, unsigned int *data)
+ struct comedi_subdevice *s,
+ struct comedi_insn *insn,
+ unsigned int *data)
{
- const struct me4000_board *board = dev->board_ptr;
int chan = CR_CHAN(insn->chanspec);
int rang = CR_RANGE(insn->chanspec);
int aref = CR_AREF(insn->chanspec);
@@ -481,13 +481,19 @@ static int me4000_ai_insn_read(struct comedi_device *dev,
break;
case AREF_DIFF:
+ if (!(s->subdev_flags && SDF_DIFF)) {
+ dev_err(dev->class_dev,
+ "Differential inputs are not available\n");
+ return -EINVAL;
+ }
+
if (rang == 0 || rang == 1) {
dev_err(dev->class_dev,
"Range must be bipolar when aref = diff\n");
return -EINVAL;
}
- if (chan >= board->ai_diff_nchan) {
+ if (chan >= (s->n_chan / 2)) {
dev_err(dev->class_dev,
"Analog input is not available\n");
return -EINVAL;
--
2.4.3
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