From 30c760c1e68b49e11a22ea0febe161e5eeb49530 Mon Sep 17 00:00:00 2001
From: Bernd Porr <mail@berndporr.me.uk>
Date: Tue, 1 Jul 2014 22:14:42 +0100
Subject: [PATCH] staging: comedi: usbduxsigma: fixing rounding error in the
range struct
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>
---
drivers/staging/comedi/drivers/usbduxsigma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
index ccc3ef7ba55c4..e869af4784c60 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -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)
}
};
--
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