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staging: comedi: me_daq: allow differential analog inputs

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The ai (*insn_read) allows differential analog inputs but the subdevice
initialization is missing the SDF_DIFF subdev_flag to allow the user to
select this mode. Fix the subdevice init.

According to the manual, differential operation only works with the
first 8 channels and bipolar ranges. Add a check to the (*insn_read) to
ensure this.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H Hartley Sweeten 2015-10-06 17:23:43 -07:00 committed by Greg Kroah-Hartman
parent 450a84e8cf
commit 8a844a91ca
1 changed files with 10 additions and 1 deletions
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11
drivers/staging/comedi/drivers/me_daq.c
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@ -246,6 +246,15 @@ static int me_ai_insn_read(struct comedi_device *dev,
unsigned short val;
int ret;
/*
* For differential operation, there are only 8 input channels
* and only bipolar ranges are available.
*/
if (aref & AREF_DIFF) {
if (chan > 7 || comedi_range_is_unipolar(s, range))
return -EINVAL;
}
/* stop any running conversion */
devpriv->ctrl1 &= ~ME_CTRL1_ADC_MODE_MASK;
writew(devpriv->ctrl1, dev->mmio + ME_CTRL1_REG);
@ -472,7 +481,7 @@ static int me_auto_attach(struct comedi_device *dev,
s = &dev->subdevices[0];
s->type = COMEDI_SUBD_AI;
s->subdev_flags = SDF_READABLE | SDF_COMMON;
s->subdev_flags = SDF_READABLE | SDF_COMMON | SDF_DIFF;
s->n_chan = 16;
s->maxdata = 0x0fff;
s->len_chanlist = 16;