The `insn_write` handler for the AO subdevice (`labpc_ao_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.
Follow the usual Comedi guidelines and change `labpc_ao_insn_write()` to
write the specified number of samples. This fixes the assumption that
`data[0]` is valid.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/ni_labpc_common.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ni_labpc_common.c b/drivers/staging/comedi/drivers/ni_labpc_common.c
index 7fa2d39562db..406952f5521d 100644
--- a/drivers/staging/comedi/drivers/ni_labpc_common.c
+++ b/drivers/staging/comedi/drivers/ni_labpc_common.c
@@ -906,7 +906,9 @@ static int labpc_ao_insn_write(struct comedi_device *dev,
{
const struct labpc_boardinfo *board = dev->board_ptr;
struct labpc_private *devpriv = dev->private;
- int channel, range;
+ unsigned int channel;
+ unsigned int range;
+ unsigned int i;
unsigned long flags;
channel = CR_CHAN(insn->chanspec);
@@ -932,9 +934,10 @@ static int labpc_ao_insn_write(struct comedi_device *dev,
devpriv->write_byte(dev, devpriv->cmd6, CMD6_REG);
}
/* send data */
- labpc_ao_write(dev, s, channel, data[0]);
+ for (i = 0; i < insn->n; i++)
+ labpc_ao_write(dev, s, channel, data[i]);
- return 1;
+ return insn->n;
}
/* lowlevel write to eeprom/dac */
--
2.19.1
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