1 files changed, 10 insertions, 15 deletions

diff --git a/drivers/staging/comedi/drivers/ni_65xx.c b/drivers/staging/comedi/drivers/ni_65xx.c
index 3ba4c5712dff..853f62b2b1a9 100644
--- a/drivers/staging/comedi/drivers/ni_65xx.c
+++ b/drivers/staging/comedi/drivers/ni_65xx.c
@@ -369,28 +369,23 @@ static int ni_65xx_dio_insn_bits(struct comedi_device *dev,
 {
         const struct ni_65xx_board *board = comedi_board(dev);
         struct ni_65xx_private *devpriv = dev->private;
-        unsigned base_bitfield_channel;
-        const unsigned max_ports_per_bitfield = 5;
+        int base_bitfield_channel;
         unsigned read_bits = 0;
-        unsigned j;
+        int last_port_offset = ni_65xx_port_by_channel(s->n_chan - 1);
+        int port_offset;
 
         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 + port_offset;
-                unsigned base_port_channel;
+        for (port_offset = ni_65xx_port_by_channel(base_bitfield_channel);
+             port_offset <= last_port_offset; port_offset++) {
+                unsigned port = sprivate(s)->base_port + port_offset;
+                int base_port_channel = port_offset * ni_65xx_channels_per_port;
                 unsigned port_mask, port_data, port_read_bits;
-                int bitshift;
-                if (port >= ni_65xx_total_num_ports(board))
+                int bitshift = base_port_channel - base_bitfield_channel;
+
+                if (bitshift >= 32)
                         break;
-                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;
-                if (bitshift >= 32 || bitshift <= -32)
-                        break;
                 if (bitshift > 0) {
                         port_mask >>= bitshift;
                         port_data >>= bitshift;