I broke `s626_set_dac()` by changing the type of the `dacdata` parameter
from `short` to `unsigned short`. It's actually designed to take a
signed value in the range -0x1fff to +0x2000 although values above
0x1fff get clamped to 0x1fff. (We could change the `maxdata` value to
0x1ffe to avoid the clamping, but `maxdata` values are usually a power
of 2 minus 1.) The bug results in all negative values passed to the
function being changed to +0x1fff by the clamp. Change the parameter
type to `int16_t` to fix the problem.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
drivers/staging/comedi/drivers/s626.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
index 6815cfe..b486099b 100644
--- a/drivers/staging/comedi/drivers/s626.c
+++ b/drivers/staging/comedi/drivers/s626.c
@@ -494,7 +494,7 @@ static void s626_send_dac(struct comedi_device *dev, uint32_t val)
* Private helper function: Write setpoint to an application DAC channel.
*/
static void s626_set_dac(struct comedi_device *dev, uint16_t chan,
- unsigned short dacdata)
+ int16_t dacdata)
{
struct s626_private *devpriv = dev->private;
uint16_t signmask;
--
1.8.4.2
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