From: Russell King <rmk+kernel@armlinux.org.uk>
To: linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, linux-omap@vger.kernel.org,
linux-oxnas@groups.io, linux-samsung-soc@vger.kernel.org,
linux-soc@vger.kernel.org
Cc: Neil Armstrong <narmstrong@baylibre.com>
Subject: [PATCH 3/9] ARM: oxnas: remove CPU hotplug implementation
Date: Thu, 13 Dec 2018 18:00:51 +0000 [thread overview]
Message-ID: <E1gXVI3-00088u-N6@rmk-PC.armlinux.org.uk> (raw)
In-Reply-To: <20181213175952.GC26090@n2100.armlinux.org.uk>
The CPU hotplug implementation on this platform is cargo-culted from
the plat-versatile implementation, and is buggy. Once a CPU hits the
"low power" loop, it will wait for pen_release to be set to the CPU
number to wake up again - but nothing in this implementation does that.
So, once a CPU has entered cpu_die() it will never, ever leave.
Remove this useless cargo-culted implementation.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
arch/arm/mach-oxnas/Makefile | 1 -
arch/arm/mach-oxnas/hotplug.c | 109 ------------------------------------------
arch/arm/mach-oxnas/platsmp.c | 4 --
3 files changed, 114 deletions(-)
delete mode 100644 arch/arm/mach-oxnas/hotplug.c
diff --git a/arch/arm/mach-oxnas/Makefile b/arch/arm/mach-oxnas/Makefile
index b625906a9970..61a34e1c0f22 100644
--- a/arch/arm/mach-oxnas/Makefile
+++ b/arch/arm/mach-oxnas/Makefile
@@ -1,2 +1 @@
obj-$(CONFIG_SMP) += platsmp.o headsmp.o
-obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
diff --git a/arch/arm/mach-oxnas/hotplug.c b/arch/arm/mach-oxnas/hotplug.c
deleted file mode 100644
index 854f29b8cba6..000000000000
--- a/arch/arm/mach-oxnas/hotplug.c
+++ /dev/null
@@ -1,109 +0,0 @@
-/*
- * Copyright (C) 2002 ARM Ltd.
- * All Rights Reserved
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-#include <linux/kernel.h>
-#include <linux/errno.h>
-#include <linux/smp.h>
-
-#include <asm/cp15.h>
-#include <asm/smp_plat.h>
-
-static inline void cpu_enter_lowpower(void)
-{
- unsigned int v;
-
- asm volatile(
- " mcr p15, 0, %1, c7, c5, 0\n"
- " mcr p15, 0, %1, c7, c10, 4\n"
- /*
- * Turn off coherency
- */
- " mrc p15, 0, %0, c1, c0, 1\n"
- " bic %0, %0, #0x20\n"
- " mcr p15, 0, %0, c1, c0, 1\n"
- " mrc p15, 0, %0, c1, c0, 0\n"
- " bic %0, %0, %2\n"
- " mcr p15, 0, %0, c1, c0, 0\n"
- : "=&r" (v)
- : "r" (0), "Ir" (CR_C)
- : "cc");
-}
-
-static inline void cpu_leave_lowpower(void)
-{
- unsigned int v;
-
- asm volatile( "mrc p15, 0, %0, c1, c0, 0\n"
- " orr %0, %0, %1\n"
- " mcr p15, 0, %0, c1, c0, 0\n"
- " mrc p15, 0, %0, c1, c0, 1\n"
- " orr %0, %0, #0x20\n"
- " mcr p15, 0, %0, c1, c0, 1\n"
- : "=&r" (v)
- : "Ir" (CR_C)
- : "cc");
-}
-
-static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
-{
- /*
- * there is no power-control hardware on this platform, so all
- * we can do is put the core into WFI; this is safe as the calling
- * code will have already disabled interrupts
- */
- for (;;) {
- /*
- * here's the WFI
- */
- asm(".word 0xe320f003\n"
- :
- :
- : "memory", "cc");
-
- if (pen_release == cpu_logical_map(cpu)) {
- /*
- * OK, proper wakeup, we're done
- */
- break;
- }
-
- /*
- * Getting here, means that we have come out of WFI without
- * having been woken up - this shouldn't happen
- *
- * Just note it happening - when we're woken, we can report
- * its occurrence.
- */
- (*spurious)++;
- }
-}
-
-/*
- * platform-specific code to shutdown a CPU
- *
- * Called with IRQs disabled
- */
-void ox820_cpu_die(unsigned int cpu)
-{
- int spurious = 0;
-
- /*
- * we're ready for shutdown now, so do it
- */
- cpu_enter_lowpower();
- platform_do_lowpower(cpu, &spurious);
-
- /*
- * bring this CPU back into the world of cache
- * coherency, and then restore interrupts
- */
- cpu_leave_lowpower();
-
- if (spurious)
- pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
-}
diff --git a/arch/arm/mach-oxnas/platsmp.c b/arch/arm/mach-oxnas/platsmp.c
index 442cc8a2f7dc..735141c0e3a3 100644
--- a/arch/arm/mach-oxnas/platsmp.c
+++ b/arch/arm/mach-oxnas/platsmp.c
@@ -19,7 +19,6 @@
#include <asm/smp_scu.h>
extern void ox820_secondary_startup(void);
-extern void ox820_cpu_die(unsigned int cpu);
static void __iomem *cpu_ctrl;
static void __iomem *gic_cpu_ctrl;
@@ -94,9 +93,6 @@ static void __init ox820_smp_prepare_cpus(unsigned int max_cpus)
static const struct smp_operations ox820_smp_ops __initconst = {
.smp_prepare_cpus = ox820_smp_prepare_cpus,
.smp_boot_secondary = ox820_boot_secondary,
-#ifdef CONFIG_HOTPLUG_CPU
- .cpu_die = ox820_cpu_die,
-#endif
};
CPU_METHOD_OF_DECLARE(ox820_smp, "oxsemi,ox820-smp", &ox820_smp_ops);
--
2.7.4
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next prev parent reply other threads:[~2018-12-13 18:01 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 17:59 [PATCH 0/9] Clean up ARM SMP/CPU hotplug implementations Russell King - ARM Linux
2018-12-13 18:00 ` [PATCH 1/9] ARM: omap2: remove unnecessary boot_lock Russell King
2018-12-13 18:00 ` [PATCH 2/9] ARM: qcom: " Russell King
2019-01-10 12:50 ` Linus Walleij
2019-01-10 20:56 ` Stephen Boyd
2019-01-10 21:47 ` Linus Walleij
2019-01-11 15:09 ` Russell King - ARM Linux
2019-01-13 22:46 ` Linus Walleij
2019-01-10 22:05 ` Stephen Boyd
2018-12-13 18:00 ` Russell King [this message]
2018-12-20 14:03 ` [PATCH 3/9] ARM: oxnas: remove CPU hotplug implementation Neil Armstrong
2018-12-13 18:00 ` [PATCH 4/9] ARM: sti: remove pen_release and boot_lock Russell King
2018-12-17 8:22 ` Patrice CHOTARD
2018-12-13 18:01 ` [PATCH 5/9] ARM: actions: remove boot_lock and pen_release Russell King
2018-12-13 18:01 ` [PATCH 6/9] ARM: vexpress/realview: consolidate immitation CPU hotplug Russell King
2018-12-13 18:01 ` [PATCH 7/9] ARM: versatile: convert boot_lock to raw Russell King
2018-12-13 18:01 ` [PATCH 8/9] ARM: versatile: rename and comment SMP implementation Russell King
2018-12-13 18:01 ` [PATCH 9/9] ARM: smp: remove arch-provided "pen_release" Russell King
2018-12-14 4:39 ` Viresh Kumar
2018-12-14 13:12 ` Russell King - ARM Linux
2018-12-17 6:16 ` Viresh Kumar
2018-12-20 10:10 ` [PATCH 0/9] Clean up ARM SMP/CPU hotplug implementations Russell King - ARM Linux
2018-12-20 10:23 ` Krzysztof Kozlowski
2018-12-20 11:05 ` Russell King - ARM Linux
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