Re: [PATCH RFC 1/3] iio: Add symlink to triggers in the device's trigger folder

[Lars-Peter Clausen]

On 05/08/2015 05:11 PM, Jonathan Cameron wrote:
> On 16/04/15 05:01, Robert Dolca wrote:
> > This patch adds a new function called iio_trigger_register_with_dev
> > which is a wrapper for iio_trigger_register. Besides the iio_trigger
> > struct this function requires iio_dev struct. It adds the trigger in
> > the device's trigger list and saves a reference to the device in the
> > trigger's struct.
> >
> > When the device is registered, in the trigger folder of the device
> > (where current_trigger file resides) a symlink is being created for
> > each trigger that was registered width iio_trigger_register_with_dev.
> >
> >   # ls -l /sys/bus/iio/devices/iio:device0/trigger/
> > total 0
> > -rw-r--r--    1 root     root          4096 Apr 16 08:33 current_trigger
> > lrwxrwxrwx    1 root     root             0 Apr 16 08:33 trigger0 -> ../../trigg
> > er0
> >
> > This should be used for device specific triggers. Doing this the user space
> > applications can figure out what if the trigger registered by a specific device
> > and what should they write in the current_trigger file. Currently some
> > applications rely on the trigger name and this does not always work.
> >
> > This implementation assumes that the trigger is registered before the device is
> > registered. If the order is not this the symlink will not be created but
> > everything else will work as before.
> >
> > Signed-off-by: Robert Dolca <robert.dolca@xxxxxxxxx>
> I was rather hoping we'd get a few more comments on this.
> In principle I like the idea, but it's new ABI and does make life
> a tiny bit more complex, so what do people think?
>
> Few trivial code comments inline.

I don't think it adds more information. Both the trigger and the device get 
registered for the same parent device, so you can already easily find the 
trigger for a device by going to the parent device and taking a look at the 
triggers registered by the parent device.

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