* Can't find trigger_now for sysfs-based triggering
@ 2021-06-12 16:43 William Huang
2021-06-13 11:18 ` Jonathan Cameron
0 siblings, 1 reply; 2+ messages in thread
From: William Huang @ 2021-06-12 16:43 UTC (permalink / raw)
To: linux-iio
Hi everyone,
I hope this is the right place to ask my noob question.
I'm trying to learn how to write an IIO driver and using a couple
books as my resource. I managed to write a simple one and perform
oneshot-based data reads (e.g. cat iio:device0/in_temp_raw).
Now, I'm trying to set up a trigger-buffered data read. I believe I
set up the triggers correctly:
cat trigger0/name > iio:device0/trigger/current_trigger
echo 1 > iio:device0/scan_elements/in_temp_en
echo 1 > iio:device0/buffer/enable
cat /dev/iio\:device0 | xxd -
Now, I'm not understanding how I should actually perform the trigger.
From my books, there should be a trigger_now file where I can echo 1
to trigger, but it's not available in my trigger0/ directory. Also,
the book references a add_trigger in /sys/devices/iio_sysfs_trigger/
directory, but that's nowhere to be found as well.
My .config also has CONFIG_IIO_SYSFS_TRIGGER=m.
Any help/advice would be appreciated!
Thanks,
William Huang
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Can't find trigger_now for sysfs-based triggering
2021-06-12 16:43 Can't find trigger_now for sysfs-based triggering William Huang
@ 2021-06-13 11:18 ` Jonathan Cameron
0 siblings, 0 replies; 2+ messages in thread
From: Jonathan Cameron @ 2021-06-13 11:18 UTC (permalink / raw)
To: William Huang; +Cc: linux-iio
On Sat, 12 Jun 2021 12:43:12 -0400
William Huang <whuang8933@gmail.com> wrote:
> Hi everyone,
>
> I hope this is the right place to ask my noob question.
> I'm trying to learn how to write an IIO driver and using a couple
> books as my resource. I managed to write a simple one and perform
> oneshot-based data reads (e.g. cat iio:device0/in_temp_raw).
>
> Now, I'm trying to set up a trigger-buffered data read. I believe I
> set up the triggers correctly:
> cat trigger0/name > iio:device0/trigger/current_trigger
Sounds like you have a trigger which is not a sysfs trigger
(probably dataready signal from some other sensor).
> echo 1 > iio:device0/scan_elements/in_temp_en
> echo 1 > iio:device0/buffer/enable
> cat /dev/iio\:device0 | xxd -
>
> Now, I'm not understanding how I should actually perform the trigger.
> From my books, there should be a trigger_now file where I can echo 1
> to trigger, but it's not available in my trigger0/ directory. Also,
> the book references a add_trigger in /sys/devices/iio_sysfs_trigger/
> directory, but that's nowhere to be found as well.
>
> My .config also has CONFIG_IIO_SYSFS_TRIGGER=m.
You will need to manually probe that module
modprobe iio-sysfs-trig
There is no simple way of autoloading that module as it's not associated
with any actual hardware.
Then you should find the /sys/devices/iio_sysfs_trigger/ directory and
can create a new instance of the sysfs trigger which should work as you
expect.
Jonathan
>
> Any help/advice would be appreciated!
>
> Thanks,
> William Huang
^ permalink raw reply [flat|nested] 2+ messages in thread
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