Fix issue with screen init causing brightness flickering and burn-in when booting HM after a splash on IPS panels

- previously, we left brightness voltage and LCD panel voltage on even though we disabled PWM and output signal, causing GSP to misdetect screen state in turn. Fix that (this fixes the issue mentioned above)

- Initialize the LCD controller over I2C, this fixes some rare sync issues some screen have with other Arm9 homebrew

This may not fix 100% of the issues, only the most egregious/dangerous
ones. There's still a lot of tech debt in Luma's baremetal code, that
necessitate a full rewrite to fix (not planned for this year)

arm9/source/i2c.h

@@ -40,6 +40,8 @@ typedef enum
     I2C_DEV_CAMERA    = 1, 	// Unconfirmed
     I2C_DEV_CAMERA2   = 2, 	// Unconfirmed
     I2C_DEV_MCU       = 3,
+    I2C_DEV_LCD_TOP   = 5,
+    I2C_DEV_LCD_BOT   = 6,
     I2C_DEV_GYRO      = 10,
     I2C_DEV_DEBUG_PAD = 12,
     I2C_DEV_IR        = 13,

arm9/source/screen.c

@@ -70,6 +70,14 @@ void prepareArm11ForFirmlaunch(void)
 void deinitScreens(void)
 {
     if(ARESCREENSINITIALIZED) invokeArm11Function(DEINIT_SCREENS);
+
+    // Backlight voltage off
+    I2C_writeReg(I2C_DEV_MCU, 0x22, 0x14);
+    wait(50);
+
+    // LCD panel voltage off
+    I2C_writeReg(I2C_DEV_MCU, 0x22, 0x01);
+    wait(50);
 }
 
 void updateBrightness(u32 brightnessIndex)
@@ -102,8 +110,31 @@ void initScreens(void)
             memcpy((void *)(ARM11_PARAMETERS_ADDRESS + 4), fbs, sizeof(fbs));
             invokeArm11Function(INIT_SCREENS);
 
-            //Turn on backlight
+            // Fragile code, needs proper fix/total rewrite of the baremetal components anyway
-            I2C_writeReg(I2C_DEV_MCU, 0x22, 0x2A);
+            // Assume controller revision is not 0x00 for either screen (this revision is extremely
+            // old and shouldn't be seen in retail units nor normal devunits)
+
+            // Controller reset off
+            I2C_writeReg(I2C_DEV_LCD_TOP, 0xFE, 0xAA);
+            I2C_writeReg(I2C_DEV_LCD_BOT, 0xFE, 0xAA);
+            wait(5);
+
+            // Controller power on
+            I2C_writeReg(I2C_DEV_LCD_TOP, 0x01, 0x10);
+            I2C_writeReg(I2C_DEV_LCD_BOT, 0x01, 0x10);
+            wait(5);
+
+            // Clear error flag
+            I2C_writeReg(I2C_DEV_LCD_TOP, 0x60, 0x00);
+            I2C_writeReg(I2C_DEV_LCD_BOT, 0x60, 0x00);
+            wait(5);
+
+            // LCD panel (bias ?) voltage on
+            I2C_writeReg(I2C_DEV_MCU, 0x22, 0x02);
+            wait(50);
+
+            // Backlight voltage on
+            I2C_writeReg(I2C_DEV_MCU, 0x22, 0x28);
             wait(5);
         }
         else updateBrightness(MULTICONFIG(BRIGHTNESS));
@@ -122,4 +153,4 @@ void initScreens(void)
 void zerofillN3dsAblRegisters(void)
 {
     invokeArm11Function(ZEROFILL_N3DS_ABL_REGISTERS);
-}
+}