x86/platform/uv/BAU: Disable software timeout on UV4 hardware

Software timeouts are not currently supported on BAU for UV4. Instead, the
BAU will rely on hardware-level fairness protocols to determine broadcast
timeouts.

Do not call enable_timeouts or calculate_destination_timeout on UV4. These
functions write to pre-UV4 MMRs so they generate error messages on UV4.

Signed-off-by: Andrew Banman <abanman@sgi.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mike Travis <travis@sgi.com>
Acked-by: Dimitri Sivanich <sivanich@sgi.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: akpm@linux-foundation.org
Cc: rja@sgi.com
Link: http://lkml.kernel.org/r/1474474161-265604-9-git-send-email-abanman@sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/platform/uv/tlb_uv.c

@@ -2109,7 +2109,8 @@ static int __init init_per_cpu(int nuvhubs, int base_part_pnode)
 	void *vp;
 	struct uvhub_desc *uvhub_descs;
 
-	timeout_us = calculate_destination_timeout();
+	if (is_uv3_hub() || is_uv2_hub() || is_uv1_hub())
+		timeout_us = calculate_destination_timeout();
 
 	vp = kmalloc(nuvhubs * sizeof(struct uvhub_desc), GFP_KERNEL);
 	uvhub_descs = (struct uvhub_desc *)vp;
@@ -2171,7 +2172,9 @@ static int __init uv_bau_init(void)
 			uv_base_pnode = uv_blade_to_pnode(uvhub);
 	}
 
-	enable_timeouts();
+	/* software timeouts are not supported on UV4 */
+	if (is_uv3_hub() || is_uv2_hub() || is_uv1_hub())
+		enable_timeouts();
 
 	if (init_per_cpu(nuvhubs, uv_base_pnode)) {
 		set_bau_off();