patch-2.1.15 linux/arch/i386/kernel/time.c

• Lines: 22
• Date: Thu Dec 12 16:51:08 1996
• Orig file: v2.1.14/linux/arch/i386/kernel/time.c
• Orig date: Tue Nov 12 15:56:02 1996

diff -u --recursive --new-file v2.1.14/linux/arch/i386/kernel/time.c linux/arch/i386/kernel/time.c
@@ -371,6 +371,21 @@
 	   closely for now.. */
 	/*smp_message_pass(MSG_ALL_BUT_SELF, MSG_RESCHEDULE, 0L, 0); */
 	    
+#ifdef CONFIG_MCA
+	if( MCA_bus ) {
+		/* The PS/2 uses level-triggered interrupts.  You can't
+		turn them off, nor would you want to (any attempt to
+		enable edge-triggered interrupts usually gets intercepted by a
+		special hardware circuit).  Hence we have to acknowledge
+		the timer interrupt.  Through some incredibly stupid
+		design idea, the reset for IRQ 0 is done by setting the
+		high bit of the PPI port B (0x61).  Note that some PS/2s,
+		notably the 55SX, work fine if this is removed.  */
+
+		irq = inb_p( 0x61 );	/* read the current state */
+		outb_p( irq|0x80, 0x61 );	/* reset the IRQ */
+	}
+#endif
 }
 
 #ifndef	CONFIG_APM	/* cycle counter may be unreliable */