Re: [PATCH] powerpc:85xx: fix timebase sync issue when CONFIG_HOTPLUG_CPU=n

When CONFIG_SMP=y, timebase synchronization is required when the second
  kernel is started.
	arch/powerpc/kernel/smp.c:
	int __cpu_up(unsigned int cpu, struct task_struct *tidle)
	{
		...
		if (smp_ops->give_timebase)
			smp_ops->give_timebase();
		...
	}

	void start_secondary(void *unused)
	{
		...
		if (smp_ops->take_timebase)
			smp_ops->take_timebase();
		...
	}

When CONFIG_HOTPLUG_CPU=n and CONFIG_KEXEC_CORE=n,
  smp_85xx_ops.give_timebase is NULL,
  smp_85xx_ops.take_timebase is NULL,
As a result, the timebase is not synchronized.

Timebase  synchronization does not depend on CONFIG_HOTPLUG_CPU.

Fixes: 56f1ba280719 ("powerpc/mpc85xx: refactor the PM operations")
Cc: <redacted> #v4.6
Signed-off-by: Xiaoming Ni <redacted>
---
  arch/powerpc/platforms/85xx/Makefile         | 2 +-
  arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c | 4 ++++
  arch/powerpc/platforms/85xx/smp.c            | 9 ++++-----
  3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/platforms/85xx/Makefile b/arch/powerpc/platforms/85xx/Makefile
index 60e4e97a929d..71ce1f6b6966 100644
--- a/arch/powerpc/platforms/85xx/Makefile
+++ b/arch/powerpc/platforms/85xx/Makefile

@@ -3,7 +3,7 @@
  # Makefile for the PowerPC 85xx linux kernel.
  #
  obj-$(CONFIG_SMP) += smp.o
-obj-$(CONFIG_FSL_PMC)		  += mpc85xx_pm_ops.o
+obj-$(CONFIG_SMP) += mpc85xx_pm_ops.o
  
  obj-y += common.o
  

diff --git a/arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c b/arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c
index 7c0133f558d0..a5656b3e9701 100644
--- a/arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c
+++ b/arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c

@@ -17,6 +17,7 @@
  
  static struct ccsr_guts __iomem *guts;
  
+#ifdef CONFIG_FSL_PMC
  static void mpc85xx_irq_mask(int cpu)
  {
  

@@ -49,6 +50,7 @@ static void mpc85xx_cpu_up_prepare(int cpu)
  {
  
  }
+#endif
  
  static void mpc85xx_freeze_time_base(bool freeze)
  {

@@ -76,10 +78,12 @@ static const struct of_device_id mpc85xx_smp_guts_ids[] = {
  
  static const struct fsl_pm_ops mpc85xx_pm_ops = {
  	.freeze_time_base = mpc85xx_freeze_time_base,
+#ifdef CONFIG_FSL_PMC
  	.irq_mask = mpc85xx_irq_mask,
  	.irq_unmask = mpc85xx_irq_unmask,
  	.cpu_die = mpc85xx_cpu_die,
  	.cpu_up_prepare = mpc85xx_cpu_up_prepare,
+#endif
  };
  
  int __init mpc85xx_setup_pmc(void)

diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
index c6df294054fe..349298cd9671 100644
--- a/arch/powerpc/platforms/85xx/smp.c
+++ b/arch/powerpc/platforms/85xx/smp.c

@@ -40,7 +40,6 @@ struct epapr_spin_table {
  	u32	pir;
  };
  
-#ifdef CONFIG_HOTPLUG_CPU
  static u64 timebase;
  static int tb_req;
  static int tb_valid;

@@ -112,6 +111,7 @@ static void mpc85xx_take_timebase(void)
  	local_irq_restore(flags);
  }
  
+#ifdef CONFIG_HOTPLUG_CPU
  static void smp_85xx_cpu_offline_self(void)
  {
  	unsigned int cpu = smp_processor_id();

@@ -499,17 +499,16 @@ void __init mpc85xx_smp_init(void)
  #ifdef CONFIG_FSL_CORENET_RCPM
  	fsl_rcpm_init();
  #endif
-
-#ifdef CONFIG_FSL_PMC
-	mpc85xx_setup_pmc();
  #endif
+	mpc85xx_setup_pmc();
  	if (qoriq_pm_ops) {
  		smp_85xx_ops.give_timebase = mpc85xx_give_timebase;
  		smp_85xx_ops.take_timebase = mpc85xx_take_timebase;
+#ifdef CONFIG_HOTPLUG_CPU
  		smp_85xx_ops.cpu_offline_self = smp_85xx_cpu_offline_self;
  		smp_85xx_ops.cpu_die = qoriq_cpu_kill;
-	}
  #endif
+	}
  	smp_ops = &smp_85xx_ops;
  
  #ifdef CONFIG_KEXEC_CORE