From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Thu, 21 Jul 2011 16:49:39 +0200 Subject: [GIT PULL] MSM fix In-Reply-To: <20110720225406.GB20310@n2100.arm.linux.org.uk> References: <20110720203703.GA4495@huya.qualcomm.com> <20110720225010.GA18381@huya.qualcomm.com> <20110720225406.GB20310@n2100.arm.linux.org.uk> Message-ID: <201107211649.39902.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thursday 21 July 2011, Russell King - ARM Linux wrote: > > It looks like it would apply to 2.6.38 and 39 as well. I'm not sure > > it qualifies under the "It must fix a real bug that bothers people". > > It would only apply if someone had set NR_CPUS to more than 2. > > Err, this makes no sense. MSM doesn't have a get_core_count function > and as far as I can see never has done in mainline. I've committed the version below now, with a clarified title. The patch looks reasonable to me, but there may be some issue I'm missing of course. The other platforms that used to have a get_core_count function no longer have that because you changed them to use scu_get_core_count, but that doesn't seem to apply to mach-msm. I did not add a stable tag though. Arnd 8<--- Subject: [PATCH] ARM: msm: platsmp: determine number of CPU cores at boot time Previously we just assumed there were CONFIG_NR_CPUS cpus present in the system. Instead, figure out the number of cpus from the MIDR register. Signed-off-by: Jeff Ohlstein Signed-off-by: David Brown [arnd: clarified patch title] Signed-off-by: Arnd Bergmann diff --git a/arch/arm/mach-msm/platsmp.c b/arch/arm/mach-msm/platsmp.c index 2034098..5ba77d0 100644 --- a/arch/arm/mach-msm/platsmp.c +++ b/arch/arm/mach-msm/platsmp.c @@ -18,6 +18,7 @@ #include #include +#include #include #include @@ -40,6 +41,12 @@ volatile int pen_release = -1; static DEFINE_SPINLOCK(boot_lock); +static inline int get_core_count(void) +{ + /* 1 + the PART[1:0] field of MIDR */ + return ((read_cpuid_id() >> 4) & 3) + 1; +} + void __cpuinit platform_secondary_init(unsigned int cpu) { /* Configure edge-triggered PPIs */ @@ -147,9 +154,9 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle) */ void __init smp_init_cpus(void) { - unsigned int i; + unsigned int i, ncores = get_core_count(); - for (i = 0; i < NR_CPUS; i++) + for (i = 0; i < ncores; i++) set_cpu_possible(i, true); set_smp_cross_call(gic_raise_softirq);