From: Johannes Berg <johannes@sipsolutions.net>
Date: Sun, 11 Dec 2005 02:41:50 +0000 (-0800)
Subject: [PATCH] ppc32: set smp_tb_synchronized on UP with SMP kernel
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ef969434005e772218c0b8086539804605070fa8;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

[PATCH] ppc32: set smp_tb_synchronized on UP with SMP kernel

ppc32 kernel, when built with CONFIG_SMP and booted on a single CPU
machine, will not properly set smp_tb_synchronized, thus causing
gettimeofday() to not use the HW timebase and to be limited to jiffy
resolution.  This, among others, causes unacceptable pauses when launching
X.org.

Signed-Off-By: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
---

diff --git a/arch/ppc/kernel/smp.c b/arch/ppc/kernel/smp.c
index 43b8fc2ca591..becbfa397556 100644
--- a/arch/ppc/kernel/smp.c
+++ b/arch/ppc/kernel/smp.c
@@ -301,6 +301,10 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 
 	/* Probe platform for CPUs: always linear. */
 	num_cpus = smp_ops->probe();
+	
+	if (num_cpus < 2)
+		smp_tb_synchronized = 1;
+	
 	for (i = 0; i < num_cpus; ++i)
 		cpu_set(i, cpu_possible_map);