We want userspace to represent the human perceived brightness.
Since the led drivers and the leds themselves don't have a
linear response to the value we give them in terms of perceived
brightness, we'll bake the curve into the dts.
The panel also doesn't have a good response under 5%, so we'll avoid
sending it anything lower than that.
Note: Ideally this patch should be coupled with the driver change from
"backlight: pwm_bl: Fix interpolation", but it can work without it,
without looking too ugly.
Signed-off-by: Alexandru Stan <amstan@xxxxxxxxxxxx>
---
arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
index bf875589d364..ccdabc6c4994 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
@@ -179,6 +179,15 @@ pp3300_fp_tp: pp3300-fp-tp-regulator {
backlight: backlight {
compatible = "pwm-backlight";
+ /* The panels don't seem to like anything below ~ 5% */
+ brightness-levels = <
+ 196 256 324 400 484 576 676 784 900 1024 1156 1296
+ 1444 1600 1764 1936 2116 2304 2500 2704 2916 3136
+ 3364 3600 3844 4096
+ >;
+ num-interpolated-steps = <64>;
+ default-brightness-level = <951>;
+
pwms = <&cros_ec_pwm 1>;
enable-gpios = <&tlmm 12 GPIO_ACTIVE_HIGH>;
power-supply = <&ppvar_sys>;
--
2.28.0
