staging: comedi: cb_pcidda: Use insn->n in AO insn_write handler

The `insn_write` handler for the AO subdevice
(`cb_pcidda_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
`cb_pcidda_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@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/cb_pcidda.c b/drivers/staging/comedi/drivers/cb_pcidda.c
index 807a31e75883ca2703331d4f5c925b0792d1936d..1d09dd265ab7e6c9007470ab5a1034fc84041efa 100644 (file)
--- a/drivers/staging/comedi/drivers/cb_pcidda.c
+++ b/drivers/staging/comedi/drivers/cb_pcidda.c
@@ -291,6 +291,7 @@ static int cb_pcidda_ao_insn_write(struct comedi_device *dev,
        unsigned int channel = CR_CHAN(insn->chanspec);
        unsigned int range = CR_RANGE(insn->chanspec);
        unsigned int ctrl;
+       unsigned int i;
 
        if (range != devpriv->ao_range[channel])
                cb_pcidda_calibrate(dev, channel, range);
@@ -317,7 +318,8 @@ static int cb_pcidda_ao_insn_write(struct comedi_device *dev,
 
        outw(ctrl, devpriv->daqio + CB_DDA_DA_CTRL_REG);
 
-       outw(data[0], devpriv->daqio + CB_DDA_DA_DATA_REG(channel));
+       for (i = 0; i < insn->n; i++)
+               outw(data[i], devpriv->daqio + CB_DDA_DA_DATA_REG(channel));
 
        return insn->n;
 }