ARM: dts: am335x: Guardian: Update backlight parameter

 * Update default brightness and dimming frequency
 * Enable current sink, while initialization
Signed-off-by: Gireesh Hiremath <Gireesh.Hiremath@in.bosch.com>
Message-Id: <20220325100613.1494-11-Gireesh.Hiremath@in.bosch.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am335x-guardian.dts

@@ -291,14 +291,34 @@ &spi0 {
 #include "tps65217.dtsi"
 
 &tps {
+  /*
+   * Configure pmic to enter OFF-state instead of SLEEP-state ("RTC-only
+   * mode") at poweroff.  Most BeagleBone versions do not support RTC-only
+   * mode and risk hardware damage if this mode is entered.
+   *
+   * For details, see linux-omap mailing list May 2015 thread
+   *  [PATCH] ARM: dts: am335x-bone* enable pmic-shutdown-controller
+   * In particular, messages:
+   *  http://www.spinics.net/lists/linux-omap/msg118585.html
+   *  http://www.spinics.net/lists/linux-omap/msg118615.html
+   *
+   * You can override this later with
+   *  &tps {  /delete-property/ ti,pmic-shutdown-controller;  }
+   * if you want to use RTC-only mode and made sure you are not affected
+   * by the hardware problems. (Tip: double-check by performing a current
+   * measurement after shutdown: it should be less than 1 mA.)
+   */
 	ti,pmic-shutdown-controller;
 	interrupt-parent = <&intc>;
 	interrupts = <7>; /* NMI */
 
 	backlight {
 		isel = <1>;  /* 1 - ISET1, 2 ISET2 */
-		fdim = <100>; /* TPS65217_BL_FDIM_100HZ */
-		default-brightness = <100>;
+		fdim = <500>; /* TPS65217_BL_FDIM_500HZ */
+		default-brightness = <50>;
+		/* 1(on) - enable current sink, while initialization */
+		/* 0(off) - disable current sink, while initialization */
+		isink-en = <1>;
 	};
 
 	regulators {
@@ -408,6 +428,13 @@ AM33XX_IOPAD(0x98c, PIN_INPUT_PULLUP | MUX_MODE0)
 		>;
 	};
 
+	led_bl_pins: gpio_led_bl_pins {
+		pinctrl-single,pins = <
+			/* P9_14, gpmc_a[2].GPIO1[18] (backlight control) */
+			AM33XX_IOPAD(0x848, PIN_OUTPUT | MUX_MODE7)
+		>;
+	};
+
 	lcd_disen_pins: pinmux_lcd_disen_pins {
 		pinctrl-single,pins = <
 			/* P9_27, mcasp0_fsr.gpio3[19] (lcd_disen) */