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staging: comedi: pcmad: fix analog input data on pcmad12 

According to the PCM-A/D-12/16 Operations Manual:

NOTE: On the PCM-A/D-12 the lower nibble of the hex value will always be 0.

Fix the pcmad_ai_insn_read() function to properly handle this by shifting
the data after it has been read.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H Hartley Sweeten 2013-06-05 15:38:57 -07:00 committed by Greg Kroah-Hartman
parent 7ecc5370de
commit 3170b2565f
1 changed files with 4 additions and 0 deletions
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4
drivers/staging/comedi/drivers/pcmad.c
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@ -104,6 +104,10 @@ static int pcmad_ai_insn_read(struct comedi_device *dev,
val = inb(dev->iobase + PCMAD_LSB) |
(inb(dev->iobase + PCMAD_MSB) << 8);
/* data is shifted on the pcmad12, fix it */
if (s->maxdata == 0x0fff)
val >>= 4;
if (pcmad_range_is_bipolar(s, range)) {
/* munge the two's complement value */
val ^= ((s->maxdata + 1) >> 1);