| Message ID | 20201021220404.v3.2.Ie4d84af5a85e8dcb8f575845518fa39f324a827d@changeid (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PWM backlight interpolation adjustments | expand |
Hi, On Wed, Oct 21, 2020 at 10:05 PM Alexandru Stan <amstan@chromium.org> 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@chromium.org> > --- > > arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 9 +++++++++ > 1 file changed, 9 insertions(+) Reviewed-by: Douglas Anderson <dianders@chromium.org>
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@chromium.org> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> > --- > > 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
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>;
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@chromium.org> --- arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 9 +++++++++ 1 file changed, 9 insertions(+)