From: Ian Abbott <abbotti@xxxxxxxxx>
I received a report that AI streaming acquisitions do not work properly
for the adl_pci9111 driver when convert_src is TRIG_TIMER and
scan_begin_src is TRIG_FOLLOW (and scan_begin_arg is therefore 0). This
seems to be down to the incorrect setting of dev_private->scan_delay in
pci9111_ai_do_cmd(). Under the previously stated conditions,
dev_private->scan_delay ends up set to (unsigned int)-1, but it ought to
be set to 0. The function sets it to 0 initially, and it only makes
sense to change it if both convert_src and scan_begin_src are set to
TRIG_TIMER.
Note: 'scan_delay' is the number of unwanted scans to discard after each
valid scan. The hardware does not support 'scan' timing as such, just a
regularly paced conversion timer (with automatic channel switching
between conversions). The driver simulates a scan period that is some
(>1) multiple of the conversion period times the scan length
(chanlist_len samples) by reading chanlist_len samples and discarding
the next scan_delay times chanlist_len samples.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/adl_pci9111.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/comedi/drivers/adl_pci9111.c b/drivers/staging/comedi/drivers/adl_pci9111.c
index 36a254c..39d112b 100644
--- a/drivers/staging/comedi/drivers/adl_pci9111.c
+++ b/drivers/staging/comedi/drivers/adl_pci9111.c
@@ -824,9 +824,12 @@ static int pci9111_ai_do_cmd(struct comedi_device *dev,
plx9050_interrupt_control(dev_private->lcr_io_base, true, true,
false, true, true);
- dev_private->scan_delay =
- (async_cmd->scan_begin_arg / (async_cmd->convert_arg *
- async_cmd->chanlist_len)) - 1;
+ if (async_cmd->scan_begin_src == TRIG_TIMER) {
+ dev_private->scan_delay =
+ (async_cmd->scan_begin_arg /
+ (async_cmd->convert_arg *
+ async_cmd->chanlist_len)) - 1;
+ }
break;
--
1.7.1
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