DMA is optional with this driver. If it was not enabled the devpriv->dma
pointer will be NULL. Fix the possible NULL pointer dereference when trying
to disable the DMA channels.
Also, tidy up the comments to fix the checkpatch.pl issues:
WARNING: line over 80 characters
Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/das1800.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c
index bdf30f8..d8f4e3f 100644
--- a/drivers/staging/comedi/drivers/das1800.c
+++ b/drivers/staging/comedi/drivers/das1800.c
@@ -458,14 +458,17 @@ static int das1800_ai_cancel(struct comedi_device *dev,
struct comedi_isadma_desc *desc;
int i;
- outb(0x0, dev->iobase + DAS1800_STATUS); /* disable conversions */
- outb(0x0, dev->iobase + DAS1800_CONTROL_B); /* disable interrupts and dma */
- outb(0x0, dev->iobase + DAS1800_CONTROL_A); /* disable and clear fifo and stop triggering */
-
- for (i = 0; i < 2; i++) {
- desc = &dma->desc[i];
- if (desc->chan)
- comedi_isadma_disable(desc->chan);
+ /* disable and stop conversions */
+ outb(0x0, dev->iobase + DAS1800_STATUS);
+ outb(0x0, dev->iobase + DAS1800_CONTROL_B);
+ outb(0x0, dev->iobase + DAS1800_CONTROL_A);
+
+ if (dma) {
+ for (i = 0; i < 2; i++) {
+ desc = &dma->desc[i];
+ if (desc->chan)
+ comedi_isadma_disable(desc->chan);
+ }
}
return 0;
--
2.6.3
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