From: Ralf Baechle <ralf@linux-mips.org>
To: linux-mips@linux-mips.org
Subject: Loongson2 cpu_wait function
Date: Thu, 23 May 2013 14:27:37 +0200 [thread overview]
Message-ID: <20130523122737.GA12530@linux-mips.org> (raw)
During the 3.10 merge cycle many MIPS platforms were broken by the
generic idle loop patches. A patch series to fix this has already been
merged but I'm wondering if fb40bc3e94933007d3e42e96daf1ec8044821cb8
[MIPS: Idle: Re-enable irqs at the end of r3081, au1k and loongson2
cpu_wait.] is sufficient and correct for Loongson 2.
In particular:
o drivers/cpufreq/loongson2_cpufreq.c protects accesses to LOONGSON_CHIPCFG0
in loongson2_cpu_wait with a spinlock. This spinlock is not used anywhere
else in the kernel so it would appear there is still a race with other
accesses to LOONGSON_CHIPCFG0.
o It's not SMPly correct - even if cpufreq_exit restores the old value of
cpu_wait on a SMP system another processor might still be executing
loongson2_cpu_wait().
o I'd appreciate if at least some basic power saving would be used even if
CONFIG_LOONGSON2_CPUFREQ was disabled, that is loongson2_cpu_wait should
go back to arch/mips/kernel/idle.c.
o Could somebody test if Loongson 2 is working? Thanks!
Ralf
next reply other threads:[~2013-05-23 12:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-23 12:27 Ralf Baechle [this message]
2013-05-23 20:28 ` Loongson2 cpu_wait function Aaro Koskinen
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