Re: [PATCH 06/13] iio: buffer: add hardware triggered buffer support

[David Lechner <dlechner@xxxxxxxxxxxx>]

On Fri, Jan 12, 2024 at 6:37 AM Jonathan Cameron
<Jonathan.Cameron@xxxxxxxxxx> wrote:
>
> On Wed, 10 Jan 2024 13:49:47 -0600
> David Lechner <dlechner@xxxxxxxxxxxx> wrote:
>
> > This adds a new mode INDIO_HW_BUFFER_TRIGGERED to the IIO subsystem.
> >
> > This mode is essentially the hardware version of INDIO_BUFFER_TRIGGERED
> > where the trigger has the semantics of INDIO_HARDWARE_TRIGGERED and the
> > buffer has the semantics of INDIO_BUFFER_HARDWARE.
> >
> > So basically INDIO_HW_BUFFER_TRIGGERED is the same as
> > INDIO_BUFFER_HARDWARE except that it also enables the trigger when the
> > buffer is enabled.
>
> If the trigger isn't routeable to multiple devices we normally don't
> make it visible at all.
>
> I'm not yet understanding what a trigger actually means in this case.
> Why do you need it to be userspace configurable?
>
> J
>

It looks like this question was answered in another thread (we need to
configure the sampling frequency from userspace). But there you
mentioned that adding a trigger for that seemed overkill. So you would
you suggest to add the sampling_frequency sysfs attribute to the
iio:deviceX instead and just forget about the trigger part? It seems a
bit odd to me to have an attribute that may or may not be there
depending other hardware external to the ADC chip. But if that is a
normal acceptable thing to do, then it does seem like the simpler
thing to do.