On 22/10/14 23:37, H Hartley Sweeten wrote:
Subdevices that set the SDF_PACKED flag return all the scan data in a single
sample. The cmd->chanlist_len is used to pass the DIO channel information to
the command and does not indicate the length (cmd->scan_end_arg) of the scan.
In general, the scan data could be packed into more than one "sample",
but you can fit 8*bytes_per_sample() 1-bit samples in each "sample". In
practice, currently only the ni_pcidio driver sets the SDF_PACKED flag
(although some other drivers ought to set it) and the whole scan will
fit into a single "sample" in that case.
Currently this flag is not handled in the comedi core files. Modify
comedi_inc_scan_progress() to automatically set the COMEDI_CB_EOS event if
the SDF_PACKED flag is set. This makes the flag work and we can remove the
events from the drivers.
Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index ff2df85..dd8f5db 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -341,12 +341,23 @@ void comedi_inc_scan_progress(struct comedi_subdevice *s,
unsigned int num_bytes)
{
struct comedi_async *async = s->async;
- unsigned int scan_length = comedi_bytes_per_scan(s);
- async->scan_progress += num_bytes;
- if (async->scan_progress >= scan_length) {
- async->scan_progress %= scan_length;
+ /*
+ * The SDF_PACKED flag indicates that the subdevice does "packed DIO".
+ *
+ * This means that all the scan data is returned in a single sample
+ * and an "end of scan" occurs for every sample.
+ */
+ if (s->subdev_flags & SDF_PACKED) {
async->events |= COMEDI_CB_EOS;
+ } else {
+ unsigned int scan_length = comedi_bytes_per_scan(s);
+
+ async->scan_progress += num_bytes;
+ if (async->scan_progress >= scan_length) {
+ async->scan_progress %= scan_length;
+ async->events |= COMEDI_CB_EOS;
+ }
}
}
EXPORT_SYMBOL_GPL(comedi_inc_scan_progress);
Is this patch even necessary? comedi_bytes_per_scan() assumes digital
samples will be packed into a whole number of "samples" and calculates
the scan length in bytes accordingly.
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=-
-=( Web: http://www.mev.co.uk/ )=-
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