Add PWM backlight support + options

- No eye blasting backlight
- Option to choose the prefered brightness
- Smooths transitions

bootloader/gfx/di.c

@@ -137,14 +137,54 @@ void display_init()
 	exec_cfg((u32 *)DISPLAY_A_BASE, _display_config_11, 113);
 }
 
+void display_backlight_pwm_init()
+{
+	clock_enable_pwm();
+
+	PWM(PWM_CONTROLLER_PWM_CSR) = (1 << 31); // Enable PWM
+
+	PINMUX_AUX(PINMUX_AUX_LCD_BL_PWM) = (PINMUX_AUX(PINMUX_AUX_LCD_BL_PWM) >> 2) << 2 | 1; // PWM clock source.
+	gpio_config(GPIO_PORT_V, GPIO_PIN_0, GPIO_MODE_SPIO); // Backlight power mode.
+	
+}
+
 void display_backlight(bool enable)
 {
-	gpio_write(GPIO_PORT_V, GPIO_PIN_0, enable ? GPIO_HIGH : GPIO_LOW); // Backlight PWM.
+	gpio_write(GPIO_PORT_V, GPIO_PIN_0, enable ? GPIO_HIGH : GPIO_LOW); // Backlight PWM GPIO.
+}
+
+void display_backlight_brightness(u32 brightness, u32 step_delay)
+{
+	u32 old_value = (PWM(PWM_CONTROLLER_PWM_CSR) >> 16) & 0xFF;
+	if (brightness == old_value)
+		return;
+
+	if (brightness > 255)
+		brightness = 255;
+
+	if (old_value < brightness)
+	{
+		for (u32 i = old_value; i < brightness + 1; i++)
+		{
+			PWM(PWM_CONTROLLER_PWM_CSR) = (1 << 31) | (i << 16); // Enable PWM
+			usleep(step_delay);
+		}
+	}
+	else
+	{
+		for (u32 i = old_value; i > brightness; i--)
+		{
+			PWM(PWM_CONTROLLER_PWM_CSR) = (1 << 31) | (i << 16); // Enable PWM
+			usleep(step_delay);
+		}
+	}
+	if (!brightness)
+	    PWM(PWM_CONTROLLER_PWM_CSR) = 0;
 }
 
 void display_end()
 {
-	display_backlight(false);
+	display_backlight_brightness(0, 1000);
 
 	DSI(_DSIREG(DSI_VIDEO_MODE_CONTROL)) = 1;
 	DSI(_DSIREG(DSI_WR_DATA)) = 0x2805;

bootloader/gfx/di.h

@@ -161,6 +161,8 @@
 #define  DE_CONTROL_ACTIVE_BLANK (4 << 2)
 
 #define DC_DISP_DC_MCCIF_FIFOCTRL 0x480
+#define DC_DISP_SD_BL_PARAMETERS 0x4D7
+#define DC_DISP_SD_BL_CONTROL 0x4DC
 #define DC_DISP_BLEND_BACKGROUND_COLOR 0x4E4
 
 #define DC_WIN_CSC_YOF 0x611
@@ -338,7 +340,11 @@
 
 #define DSI_PAD_CONTROL_4 0x52
 
+/*! Display backlight related PWM registers. */
+#define PWM_CONTROLLER_PWM_CSR 0x00
+
 void display_init();
+void display_backlight_pwm_init();
 void display_end();
 
 /*! Show one single color on the display. */
@@ -346,6 +352,7 @@ void display_color_screen(u32 color);
 
 /*! Switches screen backlight ON/OFF. */
 void display_backlight(bool enable);
+void display_backlight_brightness(u32 brightness, u32 step_delay);
 
 /*! Init display in full 1280x720 resolution (B8G8R8A8, line stride 768, framebuffer size = 1280*768*4 bytes). */
 u32 *display_init_framebuffer();

bootloader/gfx/tui.c

@@ -20,6 +20,8 @@
 #include "../config/config.h"
 #include "../power/max17050.h"
 #include "../utils/util.h"
+#include "../config/config.h"
+#include "di.h"
 
 #ifdef MENU_LOGO_ENABLE
 extern u8 *Kc_MENU_LOGO;
@@ -161,6 +163,8 @@ void *tui_do_menu(gfx_con_t *con, menu_t *menu)
 		gfx_con_setpos(con, 0,  1191);
 		gfx_printf(con, "%k VOL: Move up/down\n PWR: Select option%k", 0xFF555555, 0xFFCCCCCC);
 
+		display_backlight_brightness(h_cfg.backlight, 1000);
+
 		// Wait for user command.
 		u32 btn = btn_wait();