commit abe46b8932dd9a6dfc3698e3eb121809b7b9ed28 upstream
Reading of analog input channels by the `INSN_READ` comedi instruction
is broken for all except channel 0. `pci171x_insn_read_ai()` calls
`pci171x_ai_dropout()` with the wrong value for the third parameter. It
is supposed to be the current index in a channel list (which is always
of length 1 in this case, so the index should be 0), but instead it is
passing the actual channel number. `pci171x_ai_dropout()` checks the
channel number encoded in the raw sample value read from the hardware
matches the channel number stored in the specified index of the
previously set up channel list and returns `-ENODATA` if it doesn't
match. Since the index should always be 0 in this case, the match will
fail unless the channel number is also 0. Fix it by passing 0 as the
channel index.
Fixes: 16c7eb6047bb ("staging: comedi: adv_pci1710: always enable PCI171x_PARANOIDCHECK code")
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/adv_pci1710.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/staging/comedi/drivers/adv_pci1710.c b/drivers/staging/comedi/drivers/adv_pci1710.c
index 5539bd2..a65fa9f 100644
--- a/drivers/staging/comedi/drivers/adv_pci1710.c
+++ b/drivers/staging/comedi/drivers/adv_pci1710.c
@@ -456,7 +456,6 @@ static int pci171x_insn_read_ai(struct comedi_device *dev,
struct comedi_insn *insn, unsigned int *data)
{
struct pci1710_private *devpriv = dev->private;
- unsigned int chan = CR_CHAN(insn->chanspec);
int ret = 0;
int i;
@@ -478,7 +477,7 @@ static int pci171x_insn_read_ai(struct comedi_device *dev,
break;
val = inw(dev->iobase + PCI171x_AD_DATA);
- ret = pci171x_ai_dropout(dev, s, chan, val);
+ ret = pci171x_ai_dropout(dev, s, 0, val);
if (ret)
break;
--
2.5.1
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