Staging: comedi: ni_65xx.c: fix output inversion problem.

When reading DO subdevice with inverted outputs invert the values read
back from the ports to match the inversion of values written.

Signed-off-by: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/staging/comedi/drivers/ni_65xx.c b/drivers/staging/comedi/drivers/ni_65xx.c
index b664ce083fc5..bbf75eb6d7f2 100644
--- a/drivers/staging/comedi/drivers/ni_65xx.c
+++ b/drivers/staging/comedi/drivers/ni_65xx.c
@@ -457,6 +457,12 @@ static int ni_65xx_dio_insn_bits(struct comedi_device *dev,
                 port_read_bits =
                     readb(private(dev)->mite->daq_io_addr + Port_Data(port));
 /* printk("read 0x%x from port %i\n", port_read_bits, port); */
+                if (s->type == COMEDI_SUBD_DO && board(dev)->invert_outputs) {
+                        /* Outputs inverted, so invert value read back from
+                         * DO subdevice.  (Does not apply to boards with DIO
+                         * subdevice.) */
+                        port_read_bits ^= 0xFF;
+                }
                 if (bitshift > 0) {
                         port_read_bits <<= bitshift;
                 } else {