[PATCH 13/16] staging: comedi: comedi_test: allow read-back of AO channels

From: Ian Abbott
Date: Tue Oct 27 2015 - 13:01:39 EST

COMEDI drivers often allow the last value written to a channel on an
analog output subdevice to be read back via the "insn_read" handler.
The "comedi_test" driver does not currently support that. It is a bit
special because it loops back the last values written to the channel on
the analog output subdevice to be read back via corresponding channels
on the analog input subdevice. The "insn_read" handler for the analog
input subdevice is `waveform_ai_insn_read()`. Set that as the
"insn_read" handler for the analog output subdevice as well.

Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
drivers/staging/comedi/drivers/comedi_test.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
index a750f84..468847a 100644
--- a/drivers/staging/comedi/drivers/comedi_test.c
+++ b/drivers/staging/comedi/drivers/comedi_test.c
@@ -457,6 +457,7 @@ static int waveform_attach(struct comedi_device *dev,
s->maxdata = 0xffff;
s->range_table = &waveform_ai_ranges;
s->insn_write = waveform_ao_insn_write;
+ s->insn_read = waveform_ai_insn_read; /* do same as AI insn_read */

/* Our default loopback value is just a 0V flatline */
for (i = 0; i < s->n_chan; i++)

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