linux-kernel - [PATCH 2/4] dt-bindings: pwm-backlight: add a num-interpolation-steps property.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180110223046.17696-3-enric.balletbo@collabora.com>
Date:   Wed, 10 Jan 2018 23:30:44 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>,
        Doug Anderson <dianders@...gle.com>,
        Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>
Cc:     Jingoo Han <jingoohan1@...il.com>,
        Richard Purdie <rpurdie@...ys.net>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Brian Norris <briannorris@...gle.com>,
        Guenter Roeck <groeck@...gle.com>,
        Lee Jones <lee.jones@...aro.org>,
        Alexandru Stan <amstan@...gle.com>, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] dt-bindings: pwm-backlight: add a num-interpolation-steps property.

The num-interpolated-steps property specifies the number of
interpolated steps between each value of brightness-level table. This is
useful for high resolution PWMs to not have to list out every possible
value in the brightness-level array.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
---
 .../bindings/leds/backlight/pwm-backlight.txt       | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
index 310810906613..605432c910c5 100644
--- a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
@@ -21,6 +21,11 @@ Optional properties:
                           and enabling the backlight using GPIO.
   - pwm-off-delay-ms: Delay in ms between disabling the backlight using GPIO
                       and setting PWM value to 0.
+  - num-interpolated-steps: Number of interpolated steps between each value
+                            of brightness-levels table. This way a high
+                            resolution pwm duty cycle can be used without
+                            having to list out every possible value in the
+                            brightness-level array.
 
 [0]: Documentation/devicetree/bindings/pwm/pwm.txt
 [1]: Documentation/devicetree/bindings/gpio/gpio.txt
@@ -39,3 +44,19 @@ Example:
 		post-pwm-on-delay-ms = <10>;
 		pwm-off-delay-ms = <10>;
 	};
+
+Example using num-interpolation-steps:
+
+	backlight {
+		compatible = "pwm-backlight";
+		pwms = <&pwm 0 5000000>;
+
+		brightness-levels = <0 65535>;
+		num-interpolated-steps = <4096>;
+		default-brightness-level = <6>;
+
+		power-supply = <&vdd_bl_reg>;
+		enable-gpios = <&gpio 58 0>;
+		post-pwm-on-delay-ms = <10>;
+		pwm-off-delay-ms = <10>;
+	};
-- 
2.15.1