[PATCH 07/13] staging: comedi: pcmuio: make sure input channels stay inputs

[H Hartley Sweeten]

When updating the output channels make sure the channels configured as
inputs stay inputs.

Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
Cc: Ian Abbott <abbotti at mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/comedi/drivers/pcmuio.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/comedi/drivers/pcmuio.c b/drivers/staging/comedi/drivers/pcmuio.c
index 076a08a..5b0ade2 100644
--- a/drivers/staging/comedi/drivers/pcmuio.c
+++ b/drivers/staging/comedi/drivers/pcmuio.c
@@ -215,8 +215,14 @@ static int pcmuio_dio_insn_bits(struct comedi_device *dev,
 		s->state &= ~mask;
 		s->state |= (mask & bits);
 
-		/* invert the state and update the channels */
+		/*
+		 * Invert the state and update the channels.
+		 *
+		 * The s->io_bits mask makes sure inputs are '0' so
+		 * that the output pins stay in a high-z state.
+		 */
 		val = s->state ^ ((0x1 << s->n_chan) - 1);
+		val &= s->io_bits;
 		pcmuio_write(dev, val, asic, 0, port);
 	}
 
-- 
1.8.3.2