The `insn_write` handler for the calibration subdevice
(`ni_calib_insn_write()`) currently ignores `insn->n` (the number of
samples to write) and assumes a single sample is to be written, but
`insn->n` could be 0, meaning no samples should be written, in which
case `data[0]` is invalid.
Change `ni_calib_insn_write()` to only write to the calibration device
if `insn->n > 0`. There isn't much point writing all the values when
`insn->n > 1`, so just write the last one (`data[insn->n - 1]`).
Also follow the usual Comedi convention and return `insn->n` from the
handler to indicate success (although any non-negative return value will
do as far as the Comedi core is concerned).
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/ni_mio_common.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c b/drivers/staging/comedi/drivers/ni_mio_common.c
index 5edf59ac6706..613b6b2abf7d 100644
--- a/drivers/staging/comedi/drivers/ni_mio_common.c
+++ b/drivers/staging/comedi/drivers/ni_mio_common.c
@@ -4394,9 +4394,13 @@ static int ni_calib_insn_write(struct comedi_device *dev,
struct comedi_insn *insn,
unsigned int *data)
{
- ni_write_caldac(dev, CR_CHAN(insn->chanspec), data[0]);
+ if (insn->n) {
+ /* only bother writing the last sample to the channel */
+ ni_write_caldac(dev, CR_CHAN(insn->chanspec),
+ data[insn->n - 1]);
+ }
- return 1;
+ return insn->n;
}
static int ni_calib_insn_read(struct comedi_device *dev,
--
2.20.1
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