[PATCH 1/3] staging: comedi: cb_pcidas64: Use insn->n in AO insn_write handler
Ian Abbott
abbotti at mev.co.uk
Tue Oct 30 14:17:11 UTC 2018
The `insn_write` handler for the AO subdevice (`ao_winsn()` 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 `ao_winsn()` to write the
specified number of samples. This fixes the assumption that `data[0]`
is valid.
Signed-off-by: Ian Abbott <abbotti at mev.co.uk>
---
drivers/staging/comedi/drivers/cb_pcidas64.c | 32 ++++++++++++--------
1 file changed, 19 insertions(+), 13 deletions(-)
diff --git a/drivers/staging/comedi/drivers/cb_pcidas64.c b/drivers/staging/comedi/drivers/cb_pcidas64.c
index 631a703b345d..44e5aaf8bae5 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas64.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
@@ -3097,8 +3097,10 @@ static int ao_winsn(struct comedi_device *dev, struct comedi_subdevice *s,
{
const struct pcidas64_board *board = dev->board_ptr;
struct pcidas64_private *devpriv = dev->private;
- int chan = CR_CHAN(insn->chanspec);
- int range = CR_RANGE(insn->chanspec);
+ unsigned int chan = CR_CHAN(insn->chanspec);
+ unsigned int range = CR_RANGE(insn->chanspec);
+ unsigned int val = s->readback[chan];
+ unsigned int i;
/* do some initializing */
writew(0, devpriv->main_iobase + DAC_CONTROL0_REG);
@@ -3108,20 +3110,24 @@ static int ao_winsn(struct comedi_device *dev, struct comedi_subdevice *s,
writew(devpriv->dac_control1_bits,
devpriv->main_iobase + DAC_CONTROL1_REG);
- /* write to channel */
- if (board->layout == LAYOUT_4020) {
- writew(data[0] & 0xff,
- devpriv->main_iobase + dac_lsb_4020_reg(chan));
- writew((data[0] >> 8) & 0xf,
- devpriv->main_iobase + dac_msb_4020_reg(chan));
- } else {
- writew(data[0], devpriv->main_iobase + dac_convert_reg(chan));
+ for (i = 0; i < insn->n; i++) {
+ /* write to channel */
+ val = data[i];
+ if (board->layout == LAYOUT_4020) {
+ writew(val & 0xff,
+ devpriv->main_iobase + dac_lsb_4020_reg(chan));
+ writew((val >> 8) & 0xf,
+ devpriv->main_iobase + dac_msb_4020_reg(chan));
+ } else {
+ writew(val,
+ devpriv->main_iobase + dac_convert_reg(chan));
+ }
}
- /* remember output value */
- s->readback[chan] = data[0];
+ /* remember last output value */
+ s->readback[chan] = val;
- return 1;
+ return insn->n;
}
static void set_dac_control0_reg(struct comedi_device *dev,
--
2.19.1
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