dtoverlays: Add pwm backlight option to vc4-kms-dpi-generic

Adds the option of a PWM controlled backlight on a generic
DPI display.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

diff --git a/arch/arm/boot/dts/overlays/README b/arch/arm/boot/dts/overlays/README
index b0bb858..8a575a9 100644 (file)
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -3644,6 +3644,23 @@ Params: clock-frequency         Display clock frequency (Hz)
                                 value. NB also overridden by rgbXXX overrides.
         backlight-gpio          Defines a GPIO to be used for backlight control
                                 (default of none).
+        backlight-pwm           Defines a PWM channel to be used for backlight
+                                control (default of none). NB Disables audio
+                                headphone output as that also uses PWM.
+        backlight-pwm-chan      Choose channel on &pwm node for backlight
+                                control.
+                                (default 0).
+        backlight-pwm-gpio      GPIO pin to be used for the PWM backlight. See
+                                pwm-2chan for valid options.
+                                (default 18 - note this can only work with
+                                 rgb666-padhi).
+        backlight-pwm-func      Pin function of GPIO used for the PWM
+                                backlight.
+                                See pwm-2chan for valid options.
+                                (default 2).
+        backlight-def-brightness
+                                Set the default brightness. Normal range 1-16.
+                                (default 16).
 
 
 Name:   vc4-kms-dsi-7inch

diff --git a/arch/arm/boot/dts/overlays/vc4-kms-dpi-generic-overlay.dts b/arch/arm/boot/dts/overlays/vc4-kms-dpi-generic-overlay.dts
index 7846d56..b62c094 100644 (file)
--- a/arch/arm/boot/dts/overlays/vc4-kms-dpi-generic-overlay.dts
+++ b/arch/arm/boot/dts/overlays/vc4-kms-dpi-generic-overlay.dts
@@ -80,6 +80,52 @@
                };
        };
 
+       fragment@4 {
+               target = <&panel>;
+               __dormant__  {
+                       backlight = <&backlight_pwm>;
+               };
+       };
+
+       fragment@5 {
+               target-path = "/";
+               __dormant__  {
+                       backlight_pwm: backlight_pwm {
+                               compatible = "pwm-backlight";
+                               brightness-levels = <0 6 8 12 16 24 32 40 48 64 96 128 160 192 224 255>;
+                               default-brightness-level = <16>;
+                               pwms = <&pwm 0 200000>;
+                       };
+               };
+       };
+
+       fragment@6 {
+               target = <&pwm>;
+               __dormant__ {
+                       pinctrl-names = "default";
+                       pinctrl-0 = <&pwm_pins>;
+                       assigned-clock-rates = <1000000>;
+                       status = "okay";
+               };
+       };
+
+       fragment@7 {
+               target = <&gpio>;
+               __dormant__ {
+                       pwm_pins: pwm_pins {
+                               brcm,pins = <18>;
+                               brcm,function = <2>; /* Alt5 */
+                       };
+               };
+       };
+
+       fragment@8 {
+               target = <&audio>;
+               __dormant__  {
+                   brcm,disable-headphones;
+               };
+       };
+
        __overrides__ {
                clock-frequency = <&timing>, "clock-frequency:0";
                hactive = <&timing>, "hactive:0";
@@ -107,5 +153,10 @@
                bus-format = <&panel>, "bus-format:0";
                backlight-gpio = <0>, "+2+3",
                        <&backlight>, "gpios:4";
+               backlight-pwm = <0>, "+4+5+6+7+8";
+               backlight-pwm-chan = <&backlight_pwm>, "pwms:4";
+               backlight-pwm-gpio = <&pwm_pins>, "brcm,pins:0";
+               backlight-pwm-func = <&pwm_pins>, "brcm,function:0";
+               backlight-def-brightness = <&backlight_pwm>, "default-brightness-level:0";
        };
 };