Revert 8259 timer ack workaround

This patch was trying to work around buggy SMM bios but causes problems
by not deasserting NMI irq line (reported by Thomas Schlicht) for some
integrated local apic.

This patch was written originally as an optimization (with the side
effect to fix those bugged bios) but was never applied to 2.4 tree.

The rational was: fix your bios instead. 

Cset exclude: akpm@osdl.org|ChangeSet|20040219045328|16041

arch/i386/kernel/io_apic.c

@@ -2152,10 +2152,6 @@ static inline void check_timer(void)
 {
 	int pin1, pin2;
 	int vector;
-	unsigned int ver;
-
-	ver = apic_read(APIC_LVR);
-	ver = GET_APIC_VERSION(ver);
 
 	/*
 	 * get/set the timer IRQ vector:
@@ -2169,17 +2165,11 @@ static inline void check_timer(void)
 	 * mode for the 8259A whenever interrupts are routed
 	 * through I/O APICs.  Also IRQ0 has to be enabled in
 	 * the 8259A which implies the virtual wire has to be
-	 * disabled in the local APIC.  Finally timer interrupts
-	 * need to be acknowledged manually in the 8259A for
-	 * do_slow_timeoffset() and for the i82489DX when using
-	 * the NMI watchdog.
+	 * disabled in the local APIC.
 	 */
 	apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
 	init_8259A(1);
-	if (nmi_watchdog == NMI_IO_APIC && !APIC_INTEGRATED(ver))
-		timer_ack = 1;
-	else
-		timer_ack = !cpu_has_tsc;
+	timer_ack = 1;
 	enable_8259A_irq(0);
 
 	pin1 = find_isa_irq_pin(0, mp_INT);
@@ -2197,8 +2187,7 @@ static inline void check_timer(void)
 				disable_8259A_irq(0);
 				setup_nmi();
 				enable_8259A_irq(0);
-				if (check_nmi_watchdog() < 0);
-					timer_ack = !cpu_has_tsc;
+				check_nmi_watchdog();
 			}
 			return;
 		}
@@ -2221,8 +2210,7 @@ static inline void check_timer(void)
 				add_pin_to_irq(0, 0, pin2);
 			if (nmi_watchdog == NMI_IO_APIC) {
 				setup_nmi();
-				if (check_nmi_watchdog() < 0);
-					timer_ack = !cpu_has_tsc;
+				check_nmi_watchdog();
 			}
 			return;
 		}