Thread (21 messages) flat view 21 messages, 4 authors, 2012-08-27

[PATCH 2/6] ARM: omap: allow building omap44xx without SMP

From: Shilimkar, Santosh <hidden>
Date: 2012-08-22 15:37:03
Also in: lkml
Subsystem: cpu idle time management framework, the rest · Maintainers: "Rafael J. Wysocki", Daniel Lezcano, Linus Torvalds

On Wed, Aug 22, 2012 at 8:43 PM, Arnd Bergmann [off-list ref] wrote:
The new omap4 cpuidle implementation currently requires
ARCH_NEEDS_CPU_IDLE_COUPLED, which only works on SMP.

This patch makes it possible to build a non-SMP kernel
for that platform. This is not normally desired for
end-users but can be useful for testing.

Without this patch, building rand-0y2jSKT results in:

drivers/cpuidle/coupled.c: In function 'cpuidle_coupled_poke':
drivers/cpuidle/coupled.c:317:3: error: implicit declaration of function '__smp_call_function_single' [-Werror=implicit-function-declaration]

It's not clear if this patch is the best solution for
the problem at hand. I have made sure that we can now
build the kernel in all configurations, but that does
not mean it will actually work on an OMAP44xx.
Am not sure either about the subject patch.
quoted hunk ↗ jump to hunk
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Santosh Shilimkar <redacted>
Cc: Kevin Hilman <redacted>
Cc: Tony Lindgren <tony@atomide.com>
---
 arch/arm/mach-omap2/Kconfig       |    2 +-
 arch/arm/mach-omap2/cpuidle44xx.c |    3 ++-
 include/linux/cpuidle.h           |    4 ++++
 3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index dd2db02..66a8be3 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -62,7 +62,7 @@ config ARCH_OMAP4
        select PM_OPP if PM
        select USB_ARCH_HAS_EHCI if USB_SUPPORT
        select ARM_CPU_SUSPEND if PM
-       select ARCH_NEEDS_CPU_IDLE_COUPLED
+       select ARCH_NEEDS_CPU_IDLE_COUPLED if SMP

 config SOC_OMAP5
        bool "TI OMAP5"
diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c
index ee05e19..288bee6 100644
--- a/arch/arm/mach-omap2/cpuidle44xx.c
+++ b/arch/arm/mach-omap2/cpuidle44xx.c
@@ -238,8 +238,9 @@ int __init omap4_idle_init(void)
        for_each_cpu(cpu_id, cpu_online_mask) {
                dev = &per_cpu(omap4_idle_dev, cpu_id);
                dev->cpu = cpu_id;
+#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
                dev->coupled_cpus = *cpu_online_mask;
-
+#endif
Was just thinking whether we should just take care of it at
core cpuidle level itself. Will below be enough to kill the build
error what you mentioned in the change log ?
diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
index 2c9bf26..df34534 100644
--- a/drivers/cpuidle/coupled.c
+++ b/drivers/cpuidle/coupled.c
@@ -314,7 +314,9 @@ static void cpuidle_coupled_poke(int cpu)
        struct call_single_data *csd = &per_cpu(cpuidle_coupled_poke_cb, cpu);

        if (!cpumask_test_and_set_cpu(cpu, &cpuidle_coupled_poked_mask))
+#ifdef CONFIG_SMP
                __smp_call_function_single(cpu, csd, 0);
+#endif
 }

 /**
Regards
Santosh
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