On Wed, Oct 21, 2020 at 10:04:44PM -0700, Alexandru Stan wrote:
> 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>
Acked-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
> ---
>
> 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
