Re: [PATCH 3/9] iio: backend: add debugFs interface

["Nuno Sá" <noname.nuno@gmail.com>]

On Tue, 2024-07-16 at 19:14 +0100, Jonathan Cameron wrote:
> On Tue, 9 Jul 2024 13:14:30 +0200
> Nuno Sa <nuno.sa@analog.com> wrote:
> 
> > This adds a basic debugfs interface for backends. Two new ops are being
> > added:
> > 
> >  * debugfs_reg_access: Analogous to the core IIO one but for backend
> >    devices.
> >  * debugfs_print_chan_status: One useful usecase for this one is for
> >    testing test tones in a digital interface and "ask" the backend to
> >    dump more details on why a test tone might have errors.
> > 
> > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> Debugfs deserved docs as well as sysfs.
> Same place in Documentation/ABI/
> 
> Obviously we've neglected this in the past, but nice to do it right
> nor new stuff.
> 

I see. So you mean adding debugfs-iio?

There's one thing I'm not sure though... I'm contemplating the case where one device
may have multiple backends in which case I'm doing:

back->name = name;

where name comes from FW (DT usually). That obviously means the interface won't be
always consistent which I guess it's not a real problem for debugfs?

How would the interface look in the file? Something like?

/sys/kernel/debug/iio/iio:deviceX/<backend_name>_direct_reg_access

Or should we think in a more reliable naming? One option that came to mind is

/sys/kernel/debug/iio/iio:deviceX/backendY_direct_reg_access

where Y would be the corresponding index in io-backend-names.

One thing not optimal with the above would be identifying the actual backend device.
It would then maybe make sense having a 'backend_name' interface which I think is
likely too much just for this?

- Nuno Sá