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From:   Xiaoming Ni <nixiaoming@huawei.com>
To:     <linux-kernel@vger.kernel.org>, <oss@buserror.net>,
        <mpe@ellerman.id.au>, <benh@kernel.crashing.org>,
        <paulus@samba.org>, <paul.gortmaker@windriver.com>,
        <Yuantian.Tang@feescale.com>, <chenhui.zhao@freescale.com>,
        <linuxppc-dev@lists.ozlabs.org>
CC:     <nixiaoming@huawei.com>, <wangle6@huawei.com>,
        <wangxiongfeng2@huawei.com>
Subject: [PATCH] powerpc:85xx: fix timebase sync issue when CONFIG_HOTPLUG_CPU=n
Date:   Sun, 26 Sep 2021 10:51:44 +0800
Message-ID: <20210926025144.55674-1-nixiaoming@huawei.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7BIT
Content-Type:   text/plain; charset=US-ASCII
Precedence: bulk

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: stable@vger.kernel.org #v4.6
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
---
 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
-- 
2.27.0