New sysfs interface for privacy screens

Greg KH gregkh at
Tue Oct 1 16:27:10 UTC 2019

On Tue, Oct 01, 2019 at 10:09:46AM -0600, Mat King wrote:
> Resending in plain text mode
> 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.
> I am proposing adding a class called "privacy_screen" to interface
> with these devices. The initial API would be simple just a single
> property called "privacy_state" which when set to 1 would mean that
> privacy is enabled and 0 when privacy is disabled.
> Current known use cases will use ACPI _DSM in order to interface with
> the privacy screens, but this class would allow device driver authors
> to use other interfaces as well.
> Example:
> # get privacy screen state
> cat /sys/class/privacy_screen/cros_privacy/privacy_state # 1: privacy
> enabled 0: privacy disabled
> # set privacy enabled
> echo 1 > /sys/class/privacy_screen/cros_privacy/privacy_state

What is "cros_privacy" here?

>  Does this approach seem to be reasonable?

Seems sane to me, do you have any code that implements this so we can
see it?


greg k-h

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