powerpc: Properly handshake CPUs going out of boot spin loop

[firefly-linux-kernel-4.4.55.git] / arch / powerpc / kernel / setup_64.c

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 5a0401fcaebd2b078994d156253de9d2467c6ea7..91a5cc5f0d022237cef58a20317442993d428c8e 100644 (file)
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -72,6 +72,7 @@
 #endif
 
 int boot_cpuid = 0;
+int __initdata boot_cpu_count;
 u64 ppc64_pft_size;
 
 /* Pick defaults since we might want to patch instructions
@@ -233,6 +234,7 @@ void early_setup_secondary(void)
 void smp_release_cpus(void)
 {
        unsigned long *ptr;
+       int i;
 
        DBG(" -> smp_release_cpus()\n");
 
@@ -245,7 +247,16 @@ void smp_release_cpus(void)
        ptr  = (unsigned long *)((unsigned long)&__secondary_hold_spinloop
                        - PHYSICAL_START);
        *ptr = __pa(generic_secondary_smp_init);
-       mb();
+
+       /* And wait a bit for them to catch up */
+       for (i = 0; i < 100000; i++) {
+               mb();
+               HMT_low();
+               if (boot_cpu_count == 0)
+                       break;
+               udelay(1);
+       }
+       DBG("boot_cpu_count = %d\n", boot_cpu_count);
 
        DBG(" <- smp_release_cpus()\n");
 }