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staging: comedi: usbduxsigma: fixing rounding error in the range struct

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The AD converter on the usbsigma turns vref (2.5V/2) into the
binary value 0x780000. However the full scale range goes up to
0x800000 so that vref/2 needs to be upscaled by 0x800000/0x780000
which is 1.06bar. In the driver it's been 1.06 without the infinite
6666. I've put the fraction in the code so that the compiler can
calculate the most precise scaling value by itself.

Signed-off-by: Bernd Porr <mail@berndporr.me.uk>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bernd Porr 2014-07-01 22:14:42 +01:00 committed by Greg Kroah-Hartman
parent 0e02dcae1c
commit 30c760c1e6
1 changed files with 1 additions and 1 deletions
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2
drivers/staging/comedi/drivers/usbduxsigma.c
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@ -136,7 +136,7 @@
static const struct comedi_lrange usbduxsigma_ai_range = {
1, {
BIP_RANGE(2.65 / 2.0)
BIP_RANGE(2.5 * 0x800000 / 0x780000 / 2.0)
}
};