From 3f40a89316c8fe6ecb4a8eb66dd8d4c4e764087b Mon Sep 17 00:00:00 2001
From: "Kate J. Temkin" <k@ktemkin.com>
Date: Tue, 3 Apr 2018 03:56:50 -0600
Subject: [PATCH] fusee: don't flicker as we turn the display on

Defers backlight init until the framebuffer's fully set up.
---
 fusee/src/hwinit.h    |  3 +++
 fusee/src/hwinit/di.c | 11 ++++++++---
 fusee/src/hwinit/di.h |  4 ++++
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/fusee/src/hwinit.h b/fusee/src/hwinit.h
index 543c9638d..78a8824a0 100644
--- a/fusee/src/hwinit.h
+++ b/fusee/src/hwinit.h
@@ -28,6 +28,9 @@ void display_color_screen(u32 color);
 /*! Init display in full 1280x720 resolution (32bpp, line stride 768, framebuffer size = 1280*768*4 bytes). */
 u32 *display_init_framebuffer();
 
+/*! Enable or disable the backlight. Should only be called when the screen is completely set up, to avoid flickering. */
+void display_enable_backlight(bool on);
+
 void cluster_boot_cpu0(u64 entry, u32 ns_disable);
 
 #endif
diff --git a/fusee/src/hwinit/di.c b/fusee/src/hwinit/di.c
index 8bd7721e1..3b117c67a 100644
--- a/fusee/src/hwinit/di.c
+++ b/fusee/src/hwinit/di.c
@@ -183,14 +183,19 @@ void display_color_screen(u32 color)
 	GPIO_6(0x24) = GPIO_6(0x24) & 0xFFFFFFFE | 1;
 }
 
+void display_enable_backlight(bool on) {
+	GPIO_6(0x24) = GPIO_6(0x24) & 0xFFFFFFFE | !!on;
+}
+
+
 u32 *display_init_framebuffer(void)
 {
+	u32 *lfb_addr = (u32 *)0xC0000000;
+
 	//This configures the framebuffer @ 0xC0000000 with a resolution of 1280x720 (line stride 768).
 	exec_cfg((u32 *)DISPLAY_A_BASE, cfg_display_framebuffer, 32);
 
 	sleep(35000);
 
-	GPIO_6(0x24) = GPIO_6(0x24) & 0xFFFFFFFE | 1;
-
-	return (u32 *)0xC0000000;
+	return lfb_addr;
 }
diff --git a/fusee/src/hwinit/di.h b/fusee/src/hwinit/di.h
index 30fb1b512..a1058823c 100644
--- a/fusee/src/hwinit/di.h
+++ b/fusee/src/hwinit/di.h
@@ -2,6 +2,7 @@
 #define _DI_H_
 
 #include "types.h"
+#include <stdbool.h>
 
 /*! Display registers. */
 #define _DIREG(reg) ((reg) * 4)
@@ -53,4 +54,7 @@ void display_color_screen(u32 color);
 /*! Init display in full 1280x720 resolution (32bpp, line stride 768, framebuffer size = 1280*768*4 bytes). */
 u32 *display_init_framebuffer(void);
 
+/*! Enable or disable the backlight. Should only be called when the screen is completely set up, to avoid flickering. */
+void display_enable_backlight(bool on);
+
 #endif