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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>
This commit is contained in:
Ian Abbott 2018-10-30 14:44:16 +00:00 committed by Greg Kroah-Hartman
parent 48164754d7
commit 43818b03c5
1 changed files with 3 additions and 1 deletions
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4
drivers/staging/comedi/drivers/cb_pcidda.c
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@ -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;
}