From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Thu, 08 Jan 2015 09:53:47 +0100 Subject: [PATCH] drivers: cpuidle: don't initialize big.LITTLE driver if MCPM is unavailable In-Reply-To: <1420698544-10277-1-git-send-email-sudeep.holla@arm.com> References: <1420698544-10277-1-git-send-email-sudeep.holla@arm.com> Message-ID: <54AE459B.8010703@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/08/2015 07:29 AM, Sudeep Holla wrote: > If big.LITTLE driver is initialized even when MCPM is unavailable, > we get the below warning the first time cpu tries to enter deeper > C-states. Can you elaborate why MCPM could be unavailable when the tc2 pm code registers the mcpm platform ops before the cpuidle driver ? > ------------[ cut here ]------------ > WARNING: CPU: 4 PID: 0 at kernel/arch/arm/common/mcpm_entry.c:130 mcpm_cpu_suspend+0x6d/0x74() > Modules linked in: > CPU: 4 PID: 0 Comm: swapper/4 Not tainted 3.19.0-rc3-00007-gaf5a2cb1ad5c-dirty #11 > Hardware name: ARM-Versatile Express > [] (unwind_backtrace) from [] (show_stack+0x11/0x14) > [] (show_stack) from [] (dump_stack+0x6d/0x78) > [] (dump_stack) from [] (warn_slowpath_common+0x69/0x90) > [] (warn_slowpath_common) from [] (warn_slowpath_null+0x17/0x1c) > [] (warn_slowpath_null) from [] (mcpm_cpu_suspend+0x6d/0x74) > [] (mcpm_cpu_suspend) from [] (bl_powerdown_finisher+0x21/0x24) > [] (bl_powerdown_finisher) from [] (cpu_suspend_abort+0x1/0x14) > [] (cpu_suspend_abort) from [<00000000>] ( (null)) > ---[ end trace d098e3fd00000008 ]--- > > This patch fixes the issue by checking for the availability of MCPM > before initializing the big.LITTLE cpuidle driver > > Signed-off-by: Sudeep Holla > Cc: Lorenzo Pieralisi > Cc: Daniel Lezcano > Cc: "Rafael J. Wysocki" > --- > drivers/cpuidle/cpuidle-big_little.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/cpuidle/cpuidle-big_little.c b/drivers/cpuidle/cpuidle-big_little.c > index e3e225fe6b45..40c34faffe59 100644 > --- a/drivers/cpuidle/cpuidle-big_little.c > +++ b/drivers/cpuidle/cpuidle-big_little.c > @@ -182,6 +182,10 @@ static int __init bl_idle_init(void) > */ > if (!of_match_node(compatible_machine_match, root)) > return -ENODEV; > + > + if (!mcpm_is_available()) > + return -EUNATCH; > + > /* > * For now the differentiation between little and big cores > * is based on the part number. A7 cores are considered little > -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog