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Date:   Thu, 3 Oct 2019 11:22:54 +0100
From:   Daniel Thompson <daniel.thompson@linaro.org>
To:     Jani Nikula <jani.nikula@linux.intel.com>
Cc:     Jonathan Corbet <corbet@lwn.net>, Mat King <mathewk@google.com>,
        rafael@kernel.org, gregkh@linuxfoundation.org,
        Ross Zwisler <zwisler@google.com>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Jingoo Han <jingoohan1@gmail.com>,
        Rajat Jain <rajatja@google.com>,
        Lee Jones <lee.jones@linaro.org>,
        Alexander Schremmer <alex@alexanderweb.de>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: Re: New sysfs interface for privacy screens
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On Thu, Oct 03, 2019 at 11:19:13AM +0300, Jani Nikula wrote:
> On Wed, 02 Oct 2019, Jonathan Corbet <corbet@lwn.net> wrote:
> > On Tue, 1 Oct 2019 10:09:46 -0600
> > Mat King <mathewk@google.com> wrote:
> >
> >> I have been looking into adding Linux support for electronic privacy
> >> screens which is a feature on some new laptops which is built into the
> >> display and allows users to turn it on instead of needing to use a
> >> physical privacy filter. In discussions with my colleagues the idea of
> >> using either /sys/class/backlight or /sys/class/leds but this new
> >> feature does not seem to quite fit into either of those classes.
> >
> > FWIW, it seems that you're not alone in this; 5.4 got some support for
> > such screens if I understand things correctly:
> >
> >   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=110ea1d833ad
> 
> Oh, I didn't realize it got merged already, I thought this was
> related...
> 
> So we've already replicated the backlight sysfs interface problem for
> privacy screens. :(

I guess... although the Thinkpad code hasn't added any standard
interfaces (no other laptop should be placing controls for a privacy
screen in /proc/acpi/ibm/... ). Maybe its not too late.


Daniel.