Re: [RFC v2] iio: input-bridge: optionally bridge iio acceleometers to create a /dev/input interface

From: H. Nikolaus Schaller
Date: Fri May 10 2019 - 06:07:57 EST

> Am 10.05.2019 um 11:35 schrieb Bastien Nocera <hadess@xxxxxxxxxx>:
> On Fri, 2019-05-10 at 11:33 +0200, H. Nikolaus Schaller wrote:
> <snip>
>> It does through "Input device name:" starting with "iio-bridge:" as
>> you can see in the commit message of [RFC v3]:
> This makes it ABI, right?

The "Input device name:" is already ABI of the input system (although I guess the string is
built into the evtest tool). I think there are also /sys nodes which carry the same information.

But yes, if someone changes the "iio-bridge:" prefix in kernel code it breaks a user space lib
making use of it:

+ poll_dev->input->name = kasprintf(GFP_KERNEL, "iio-bridge: %s",
+ indio_dev->name);
+ poll_dev->input->phys = kasprintf(GFP_KERNEL, "iio:device%d",
+ indio_dev->id);

This type of exporting names seems to be quite common. E.g. "mmcblk0p1" which may end up
in some /etc/fstab.

> Big fat warnings around the code that declares it would be appreciated.