From 20fb170b293218ef66ce885df3a77903e3d11572 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Wed, 18 Sep 2013 11:47:26 -0700 Subject: [PATCH] staging: comedi: adl_pci6208: save raw data for analog output readback This driver munges the raw data from the comedi core into its two's complement form before writing it to the hardware. The last value written to the hardware is saved in the private data for readback. Since the comedi core always expects the data to be in offset binary coding, make sure to save the un-munged value for readback. Also, prefetch the current readback value before attempting to update the hardware. This ensures that the readback value is correct if no values are actually written. Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/adl_pci6208.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/staging/comedi/drivers/adl_pci6208.c b/drivers/staging/comedi/drivers/adl_pci6208.c index 60f1f5c9532d..9150582fad06 100644 --- a/drivers/staging/comedi/drivers/adl_pci6208.c +++ b/drivers/staging/comedi/drivers/adl_pci6208.c @@ -88,21 +88,21 @@ static int pci6208_ao_winsn(struct comedi_device *dev, { struct pci6208_private *devpriv = dev->private; int chan = CR_CHAN(insn->chanspec); - unsigned long invert = 1 << (16 - 1); - unsigned long value = 0; + unsigned int invert = 1 << (16 - 1); + unsigned int val = devpriv->ao_readback[chan]; unsigned short status; int i; for (i = 0; i < insn->n; i++) { - value = data[i] ^ invert; + val = data[i]; do { status = inw(dev->iobase + PCI6208_AO_STATUS); } while (status & PCI6208_AO_STATUS_DATA_SEND); - outw(value, dev->iobase + PCI6208_AO_CONTROL(chan)); + outw(val ^ invert, dev->iobase + PCI6208_AO_CONTROL(chan)); } - devpriv->ao_readback[chan] = value; + devpriv->ao_readback[chan] = val; return insn->n; } -- 2.39.5