Staging: comedi: ni_65xx.c: fix insn_bits shift calculation.

Fix insn_bits bitshift calculation for subdevice with non-zero
base_port.

Thanks to cJ-comedi at zougloub dot eu for spotting the bug.

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

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/staging/comedi/drivers/ni_65xx.c b/drivers/staging/comedi/drivers/ni_65xx.c
index 6b118c15b49..b664ce083fc 100644
--- a/drivers/staging/comedi/drivers/ni_65xx.c
+++ b/drivers/staging/comedi/drivers/ni_65xx.c
@@ -418,15 +418,15 @@ static int ni_65xx_dio_insn_bits(struct comedi_device *dev,
                 return -EINVAL;
         base_bitfield_channel = CR_CHAN(insn->chanspec);
         for (j = 0; j < max_ports_per_bitfield; ++j) {
+                const unsigned port_offset = ni_65xx_port_by_channel(base_bitfield_channel) + j;
                 const unsigned port =
-                    sprivate(s)->base_port +
-                    ni_65xx_port_by_channel(base_bitfield_channel) + j;
+                    sprivate(s)->base_port + port_offset;
                 unsigned base_port_channel;
                 unsigned port_mask, port_data, port_read_bits;
                 int bitshift;
                 if (port >= ni_65xx_total_num_ports(board(dev)))
                         break;
-                base_port_channel = port * ni_65xx_channels_per_port;
+                base_port_channel = port_offset * ni_65xx_channels_per_port;
                 port_mask = data[0];
                 port_data = data[1];
                 bitshift = base_port_channel - base_bitfield_channel;