On Tue, Jan 27, 2015 at 11:49:49AM +0200, Priit Laes wrote:

On Tue, 2015-01-27 at 10:18 +0100, Maxime Ripard wrote:

quoted

Hi,

On Mon, Jan 26, 2015 at 06:58:32PM +0200, Priit Laes wrote:

quoted

---

Like Hans was pointing out, commit log and signed-off-by please

quoted

 .../ABI/testing/sysfs-driver-input-sun4i-lradc     |  4 ++
 drivers/input/keyboard/sun4i-lradc-keys.c          | 49 
+++++++++++++++++-----
 2 files changed, 43 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-input-
sun4i-lradc

diff --git a/Documentation/ABI/testing/sysfs-driver-input-sun4i-

lradc b/Documentation/ABI/testing/sysfs-driver-input-sun4i-lradc
new file mode 100644
index 0000000..e4e6448

--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-input-sun4i-lradc

@@ -0,0 +1,4 @@
+What:          /sys/class/input/input(x)/device/voltage
+Date:          February 2015
+Contact:       Priit Laes <plaes-q/aMd4JkU83YtjvyW6yDsg@public.gmane.org>
+Description:   ADC output voltage in microvolts or 0 if device is 

not opened.

Why is it returning 0 when "device is not opened" ? What does that 
even mean? You can't read that file without opening it.

It means that something has to open the /dev/input/inputX device which 
sets up the ADC before the voltage can be read from the sysfs file.

I'd consider this a bug. Why someone has to use an unrelated interface for
another interface to work correctly?

[...]

quoted

As I told you already, if you're going to expose this an ADC in the 
end, the proper solution is to use the IIO framework, not adding a 
custom sysfs file.

My intention was to expose just a simple debug output, so one can 
press the buttons and read the voltages for devicetree keymap.

If anyone can suggest a simpler approach than current sysfs based one, 
I would do it. But full blown iio driver is currently out of scope. 
Also, Carlo's (ccaione) initially submitted (?) driver for lradc 
utilized iio subsystem.

For stuff like this debugfs (AKA dumping ground) is better suited as it does
not establish ABI.  i

Thanks.

-- 
Dmitry