From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757319AbbA0Jt5 (ORCPT ); Tue, 27 Jan 2015 04:49:57 -0500 Received: from gn237.zone.eu ([217.146.67.237]:26898 "EHLO gn237.zone.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751443AbbA0Jtz (ORCPT ); Tue, 27 Jan 2015 04:49:55 -0500 Message-ID: <1422352189.23189.12.camel@plaes.org> Subject: Re: [linux-sunxi] Re: [PATCH] arm: sunxi: input: RFC: Add sysfs voltage for sun4i-lradc driver From: Priit Laes To: Maxime Ripard Cc: linux-sunxi@googlegroups.com, Hans de Goede , Dmitry Torokhov , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org Date: Tue, 27 Jan 2015 11:49:49 +0200 In-Reply-To: <20150127091829.GD7200@lukather> References: <1422291516-24895-1-git-send-email-plaes@plaes.org> <20150127091829.GD7200@lukather> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.13.9 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2015-01-27 at 10:18 +0100, Maxime Ripard wrote: > Hi, > > On Mon, Jan 26, 2015 at 06:58:32PM +0200, Priit Laes wrote: > > --- > > Like Hans was pointing out, commit log and signed-off-by please > > > .../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 > > +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. [...] > > 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. Päikest, Priit :)