From be1b3b1ab35f13671af1ff452b2814ad85725b3d Mon Sep 17 00:00:00 2001
From: Mateusz Faderewski <sc@mateuszfaderewski.pl>
Date: Sun, 27 Aug 2023 18:52:03 +0200
Subject: [PATCH] Boot improvements

---
 src/boot/boot.c    |  2 +-
 src/boot/boot_io.h |  2 ++
 src/boot/reboot.S  | 54 ++++++++++++++++++++++++++++++++++++++--------
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/src/boot/boot.c b/src/boot/boot.c
index 901c2eb9..da6035d5 100644
--- a/src/boot/boot.c
+++ b/src/boot/boot.c
@@ -93,7 +93,7 @@ void boot (boot_params_t *params) {
     while (cpu_io_read(&SP->DMA_BUSY));
 
     cpu_io_write(&PI->SR, PI_SR_CLR_INTR | PI_SR_RESET);
-    while (cpu_io_read(&VI->CURR_LINE) != 2);
+    while ((cpu_io_read(&VI->CURR_LINE) & ~(VI_CURR_LINE_FIELD)) != 0);
     cpu_io_write(&VI->V_INTR, 0x3FF);
     cpu_io_write(&VI->H_LIMITS, 0);
     cpu_io_write(&VI->CURR_LINE, 0);
diff --git a/src/boot/boot_io.h b/src/boot/boot_io.h
index 1029d99c..2eede3b5 100644
--- a/src/boot/boot_io.h
+++ b/src/boot/boot_io.h
@@ -157,6 +157,8 @@ typedef struct {
 #define VI_CR_PIXEL_ADVANCE_3       (1 << 15)
 #define VI_CR_DITHER_FILTER_ON      (1 << 16)
 
+#define VI_CURR_LINE_FIELD          (1 << 0)
+
 
 typedef struct {
     io32_t MADDR;
diff --git a/src/boot/reboot.S b/src/boot/reboot.S
index ef716650..3e5c5c1a 100644
--- a/src/boot/reboot.S
+++ b/src/boot/reboot.S
@@ -7,14 +7,15 @@
 #define RI_REFRESH          0x10
 #define RI_LATENCY          0x14
 
-#define RI_MODE_RESET       0x0000000C
+#define RI_MODE_RESET       0x00000000
 #define RI_MODE_STANDBY     0x0000000E
 
 #define RDRAM_RESET_DELAY   1024
+#define RDRAM_STANDBY_DELAY 512
 
 #define IPL3_ENTRY          0xA4000040
 
-
+.set noat
 .section .text.reboot, "ax", %progbits
 .type reboot, %object
 reboot_start:
@@ -22,7 +23,6 @@ reboot_start:
 
 # NOTE: CIC x105 requirement
 ipl2:
-.set noat
 .set noreorder
     lui $t5, 0xBFC0
 1:
@@ -34,30 +34,66 @@ ipl2:
     lw $t0, 0x24($t5)
     lui $t3, 0xB000
 .set reorder
-.set at
 
 reboot_entry:
     .equ reboot_entry_offset, ((. - reboot_start) / 4)
     .global reboot_entry_offset
 
+    bnez $s5, reset_rdram_skip
+
 reset_rdram:
     li $t0, RI_ADDRESS
 
     li $t1, RI_MODE_RESET
     sw $t1, RI_MODE($t0)
+
+    li $t2, RDRAM_RESET_DELAY
+1:
+    addiu $t2, (-1)
+    bnez $t2, 1b
+
     sw $zero, RI_CONFIG($t0)
     sw $zero, RI_CURRENT_LOAD($t0)
     sw $zero, RI_SELECT($t0)
     sw $zero, RI_REFRESH($t0)
 
-    li $t2, RDRAM_RESET_DELAY
-delay:
-    addiu $t2, $t2, (-1)
-    bnez $t2, delay
-
     li $t1, RI_MODE_STANDBY
     sw $t1, RI_MODE($t0)
 
+    li $t2, RDRAM_STANDBY_DELAY
+1:
+    addiu $t2, (-1)
+    bnez $t2, 1b
+reset_rdram_skip:
+
+    move $at, $zero
+    move $v0, $zero
+    move $v1, $zero
+    move $a0, $zero
+    move $a1, $zero
+    move $a2, $zero
+    move $a3, $zero
+    move $t0, $zero
+    move $t1, $zero
+    move $t2, $zero
+    move $t3, $zero
+    move $t4, $zero
+    move $t5, $zero
+    move $t6, $zero
+    move $t7, $zero
+    move $s0, $zero
+    move $s1, $zero
+    move $s2, $zero
+    move $t8, $zero
+    move $t9, $zero
+    move $k0, $zero
+    move $k1, $zero
+    move $gp, $zero
+    move $s8, $zero
+    move $ra, $zero
+
+    mtc0 $zero, $9
+
 run_ipl3:
     li $t3, IPL3_ENTRY
     jr $t3