`devpriv->ao_timer` is used while an asynchronous command is running on
the AO subdevice. It also gets modified by the subdevice's `cmdtest`
handler for checking new asynchronous commands,
`usbduxsigma_ao_cmdtest()`, which is not correct as it's allowed to
check new commands while an old command is still running. Fix it by
moving the code which sets up `devpriv->ao_timer` into the subdevice's
`cmd` handler, `usbduxsigma_ao_cmd()`.
Note that the removed code in `usbduxsigma_ao_cmdtest()` checked that
`devpriv->ao_timer` did not end up less that 1, but that could not
happen due because `cmd->scan_begin_arg` or `cmd->convert_arg` had
already been range-checked.
Also note that we tested the `high_speed` variable in the old code, but
that is currently always 0 and means that we always use "scan" timing
(`cmd->scan_begin_src == TRIG_TIMER` and `cmd->convert_src == TRIG_NOW`)
and never "convert" (individual sample) timing (`cmd->scan_begin_src ==
TRIG_FOLLOW` and `cmd->convert_src == TRIG_TIMER`). The moved code
tests `cmd->convert_src` instead to decide whether "scan" or "convert"
timing is being used, although currently only "scan" timing is
supported.
Fixes: fb1ef622e7a3 ("staging: comedi: usbduxsigma: tidy up analog output command support")
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.19 onwards
---
drivers/staging/comedi/drivers/usbduxsigma.c | 33 ++++++++++++----------------
1 file changed, 14 insertions(+), 19 deletions(-)
diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
index 22517de..dc0b25a 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -912,25 +912,6 @@ static int usbduxsigma_ao_cmdtest(struct comedi_device *dev,
if (err)
return 3;
- /* Step 4: fix up any arguments */
-
- /* we count in timer steps */
- if (high_speed) {
- /* timing of the conversion itself: every 125 us */
- devpriv->ao_timer = cmd->convert_arg / 125000;
- } else {
- /*
- * timing of the scan: every 1ms
- * we get all channels at once
- */
- devpriv->ao_timer = cmd->scan_begin_arg / 1000000;
- }
- if (devpriv->ao_timer < 1)
- err |= -EINVAL;
-
- if (err)
- return 4;
-
return 0;
}
@@ -943,6 +924,20 @@ static int usbduxsigma_ao_cmd(struct comedi_device *dev,
down(&devpriv->sem);
+ if (cmd->convert_src == TRIG_TIMER) {
+ /*
+ * timing of the conversion itself: every 125 us
+ * at high speed (not used yet)
+ */
+ devpriv->ao_timer = cmd->convert_arg / 125000;
+ } else {
+ /*
+ * timing of the scan: every 1ms
+ * we get all channels at once
+ */
+ devpriv->ao_timer = cmd->scan_begin_arg / 1000000;
+ }
+
devpriv->ao_counter = devpriv->ao_timer;
if (cmd->start_src == TRIG_NOW) {
--
2.1.4
--
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