On Monday, August 24, 2015 6:36 AM, Ian Abbott wrote: > On 17/08/15 19:31, H Hartley Sweeten wrote: >> The analog inputs have 12-bit resoultion. The subdevice 'maxdata' is >> a mask value for the resolution. Fix the value. >> >> Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx> >> Cc: Ian Abbott <abbotti@xxxxxxxxx> >> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> >> --- >> drivers/staging/comedi/drivers/usbduxfast.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/staging/comedi/drivers/usbduxfast.c b/drivers/staging/comedi/drivers/usbduxfast.c >> index 60f1c5e..c8687b0 100644 >> --- a/drivers/staging/comedi/drivers/usbduxfast.c >> +++ b/drivers/staging/comedi/drivers/usbduxfast.c >> @@ -865,7 +865,7 @@ static int usbduxfast_attach_common(struct comedi_device *dev) >> s->do_cmdtest = usbduxfast_ai_cmdtest; >> s->do_cmd = usbduxfast_ai_cmd; >> s->cancel = usbduxfast_ai_cancel; >> - s->maxdata = 0x1000; >> + s->maxdata = 0x0fff; >> s->range_table = &range_usbduxfast_ai_range; >> >> up(&devpriv->sem); >> > > I've just got confirmation from the driver author Bernd Porr, that the > maximum value it can produce is 0x1000, not 0xfff. This is due to an > overflow bit from the ADC. > > Probably best not to mess with it for now, as the current comedilib > library's 'comedi_to_phys()' function returns NAN by default if the raw > value is either 0 or maxdata as that means the value is probably pegged. > However, it does not currently return NAN for raw values above maxdata > (although it probably ought to). Ian, Good to know. Will drop this patch and update the series. I'll also add a comment about the odd 0x1000 maxdata so that it will not get "fixed" in the future. Thanks, Hartley _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
