From 1e85c1ea1ff2a60659e790ef8ec76c7339445841 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Wed, 5 Feb 2014 14:59:53 -0700 Subject: [PATCH] staging: comedi: adv_pci1710: fix analog output readback value The last value written to a analog output channel is cached in the private data of this driver for readback. Currently, the wrong value is cached in the (*insn_write) functions. The current code stores the data[n] value for readback afer the loop has written all the values. At this time 'n' points past the end of the data array. Fix the functions by using a local variable to hold the data being written to the analog output channel. This variable is then used after the loop is complete to store the readback value. The current value is retrieved before the loop in case no values are actually written.. Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/adv_pci1710.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/staging/comedi/drivers/adv_pci1710.c b/drivers/staging/comedi/drivers/adv_pci1710.c index 593676cf706a..d9ad2c0fdda2 100644 --- a/drivers/staging/comedi/drivers/adv_pci1710.c +++ b/drivers/staging/comedi/drivers/adv_pci1710.c @@ -494,6 +494,7 @@ static int pci171x_insn_write_ao(struct comedi_device *dev, struct comedi_insn *insn, unsigned int *data) { struct pci1710_private *devpriv = dev->private; + unsigned int val; int n, chan, range, ofs; chan = CR_CHAN(insn->chanspec); @@ -509,11 +510,14 @@ static int pci171x_insn_write_ao(struct comedi_device *dev, outw(devpriv->da_ranges, dev->iobase + PCI171x_DAREF); ofs = PCI171x_DA1; } + val = devpriv->ao_data[chan]; - for (n = 0; n < insn->n; n++) - outw(data[n], dev->iobase + ofs); + for (n = 0; n < insn->n; n++) { + val = data[n]; + outw(val, dev->iobase + ofs); + } - devpriv->ao_data[chan] = data[n]; + devpriv->ao_data[chan] = val; return n; @@ -679,6 +683,7 @@ static int pci1720_insn_write_ao(struct comedi_device *dev, struct comedi_insn *insn, unsigned int *data) { struct pci1710_private *devpriv = dev->private; + unsigned int val; int n, rangereg, chan; chan = CR_CHAN(insn->chanspec); @@ -688,13 +693,15 @@ static int pci1720_insn_write_ao(struct comedi_device *dev, outb(rangereg, dev->iobase + PCI1720_RANGE); devpriv->da_ranges = rangereg; } + val = devpriv->ao_data[chan]; for (n = 0; n < insn->n; n++) { - outw(data[n], dev->iobase + PCI1720_DA0 + (chan << 1)); + val = data[n]; + outw(val, dev->iobase + PCI1720_DA0 + (chan << 1)); outb(0, dev->iobase + PCI1720_SYNCOUT); /* update outputs */ } - devpriv->ao_data[chan] = data[n]; + devpriv->ao_data[chan] = val; return n; } -- 2.20.1