[PATCH] staging: comedi: adl_pci7x3x: fix digital output on PCI-7230

[Ian Abbott]

The "adl_pci7x3x" driver replaced the "adl_pci7230" and "adl_pci7432"
drivers in commits 8f567c373c4b ("staging: comedi: new adl_pci7x3x
driver") and 657f77d173d3 ("staging: comedi: remove adl_pci7230 and
adl_pci7432 drivers").  Although the new driver code agrees with the
user manuals for the respective boards, digital outputs stopped working
on the PCI-7230.  This has 16 digital output channels and the previous
adl_pci7230 driver shifted the 16 bit output state left by 16 bits
before writing to the hardware register.  The new adl_pci7x3x driver
doesn't do that.  Fix it in `adl_pci7x3x_do_insn_bits()` by checking
for the special case of the subdevice having only 16 channels and
duplicating the 16 bit output state into both halves of the 32-bit
register.  That should work both for what the board actually does and
for what the user manual says it should do.

Fixes: 8f567c373c4b ("staging: comedi: new adl_pci7x3x driver")
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.13+, needs backporting for 3.7 to 3.12
---
 drivers/staging/comedi/drivers/adl_pci7x3x.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/comedi/drivers/adl_pci7x3x.c b/drivers/staging/comedi/drivers/adl_pci7x3x.c
index 934af3f..b0fc027 100644
--- a/drivers/staging/comedi/drivers/adl_pci7x3x.c
+++ b/drivers/staging/comedi/drivers/adl_pci7x3x.c
@@ -120,8 +120,20 @@ static int adl_pci7x3x_do_insn_bits(struct comedi_device *dev,
 {
 	unsigned long reg = (unsigned long)s->private;
 
-	if (comedi_dio_update_state(s, data))
-		outl(s->state, dev->iobase + reg);
+	if (comedi_dio_update_state(s, data)) {
+		unsigned int val = s->state;
+
+		if (s->n_chan == 16) {
+			/*
+			 * It seems the PCI-7230 needs the 16-bit DO state
+			 * to be shifted left by 16 bits before being written
+			 * to the 32-bit register.  Set the value in both
+			 * halves of the register to be sure.
+			 */
+			val |= val << 16;
+		}
+		outl(val, dev->iobase + reg);
+	}
 
 	data[1] = s->state;
 
-- 
2.5.0

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