Revert "[PATCH] x86_64: Only do the clustered systems have unsynchronized TSC assumption on IBM systems"

This reverts commit 13a229abc25640813f1480c0478dfc6bdbc1c19e.

Quoth Andi:
"After some consideration and feedback from various people it turns
out this wasn't that good an idea. It has some problems and needs
more work. Since it was only an optimization anyways it's best to
just back it out again for now."

Signed-off-by: Linus Torvalds <[e-mail]>

arch/i386/kernel/acpi/boot.c

···
 extern int gsi_irq_sharing(int gsi);
 #include <asm/proto.h>
 
+static inline int acpi_madt_oem_check(char *oem_id, char *oem_table_id) { return 0; }
+
+
 #else				/* X86 */
 
 #ifdef	CONFIG_X86_LOCAL_APIC

arch/x86_64/kernel/apic.c

···
 	irq_exit();
 }
 
-int __initdata unsync_tsc_on_multicluster;
-
 /*
  * oem_force_hpet_timer -- force HPET mode for some boxes.
  *
  * Thus far, the major user of this is IBM's Summit2 series:
  *
- * Some clustered boxes may have unsynced TSC problems if they are
+ * Clustered boxes may have unsynced TSC problems if they are
  * multi-chassis. Use available data to take a good guess.
  * If in doubt, go HPET.
  */
···
 	int i, clusters, zeros;
 	unsigned id;
 	DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);
-
-	/* Only do this check on IBM machines - big Unisys systems
-	   use multiple clusters too, but have synchronized TSC */
-	if (!unsync_tsc_on_multicluster)
-		return 0;
 
 	bitmap_zero(clustermap, NUM_APIC_CLUSTERS);
 

include/asm-x86_64/acpi.h

···
 
 extern int acpi_skip_timer_override;
 
-extern int unsync_tsc_on_multicluster;
-
-static inline int acpi_madt_oem_check(char *oem, char *productid) 
-{ 
-	/* Copied from i386. Probably has too many entries. */
-	if (!strncmp(oem, "IBM ENSW", 8) && 
-        	(!strncmp(productid, "VIGIL SMP", 9) 
-             		|| !strncmp(productid, "EXA", 3)
-			|| !strncmp(productid, "RUTHLESS SMP", 12))) {
-		unsync_tsc_on_multicluster = 1;
-        }
-        return 0;
-}
-
 #endif /*__KERNEL__*/
 
 #endif /*_ASM_ACPI_H*/