# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1511213096 -3600
# Node ID c9ec1da2c3ca0c897958ae60eb30f189193fba46
# Parent  11840489990bf3ec63aff01351a7fec57be3b6d0
Enable and disable the DMA channel rather than changing IRQ settings.

diff -r 11840489990b -r c9ec1da2c3ca vga.S
--- a/vga.S	Mon Nov 20 22:14:55 2017 +0100
+++ b/vga.S	Mon Nov 20 22:24:56 2017 +0100
@@ -530,12 +530,10 @@
 	occurs:
 	DCHxECON<15:8> = CHSIRQ<7:0> = timer 2 interrupt
 	DCHxECON<4> = SIRQEN = 1
-
-	For now, however, prevent initiation by not setting SIRQEN.
 	*/
 
 	la $v0, DCH0ECON
-	li $v1, (9 << 8)
+	li $v1, (9 << 8) | (1 << 4)
 	sw $v1, 0($v0)
 
 	/*
@@ -643,11 +641,7 @@
 	li $v1, (1 << 28)	/* IEC1<28> = DMA0IE = 1 */
 	sw $v1, SET($v0)
 
-	/* Enable line channel. */
-
-	la $v0, DCH0CON
-	li $v1, 0b10000000
-	sw $v1, SET($v0)
+	/* Enable line channel later. */
 
 	jr $ra
 	nop
@@ -858,8 +852,8 @@
 
 	/* Enable the line channel for timer event transfer initiation. */
 
-	la $v0, DCH0ECON
-	li $v1, (1 << 4)	/* DCH0ECON<4> = SIRQEN = 1 */
+	la $v0, DCH0CON
+	li $v1, (1 << 7)
 	sw $v1, SET($v0)
 
 _vbp_active_ret:
@@ -883,8 +877,8 @@
 
 	/* Disable the line channel. */
 
-	la $v0, DCH0ECON
-	li $v1, (1 << 4)	/* DCH0ECON<4> = SIRQEN = 0 */
+	la $v0, DCH0CON
+	li $v1, (1 << 7)
 	sw $v1, CLR($v0)
 
 _visible_active_ret: