[PATCH] ARM: EXYNOS: cpuidle: Skip C1 cpuidle state for exynos5440
daniel.lezcano at linaro.org
Sun Jul 28 06:31:51 EDT 2013
On 07/28/2013 11:22 AM, Tomasz Figa wrote:
> On Sunday 28 of July 2013 09:10:09 Daniel Lezcano wrote:
>> On 07/24/2013 01:47 PM, Kukjin Kim wrote:
>>> Amit Daniel Kachhap wrote:
>>>> This patch skips the deep C1(AFTR -Arm off top running) state for
>>>> soc as this soc does not support this state. All the cpu's only
>>>> allows the basic
>>>> C0 state.
>>>> Signed-off-by: Amit Daniel Kachhap <amit.daniel at samsung.com>
>>>> arch/arm/mach-exynos/cpuidle.c | 2 +-
>>>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>>> diff --git a/arch/arm/mach-exynos/cpuidle.c b/arch/arm/mach-
>>>> index 17a18ff..9a776a1 100644
>>>> --- a/arch/arm/mach-exynos/cpuidle.c
>>>> +++ b/arch/arm/mach-exynos/cpuidle.c
>>>> @@ -210,7 +210,7 @@ static int __init exynos4_init_cpuidle(void)
>>>> device->cpu = cpu_id;
>>>> /* Support IDLE only */
>>>> - if (cpu_id != 0)
>>>> + if (soc_is_exynos5440() || cpu_id != 0)
>>>> device->state_count = 1;
>>>> ret = cpuidle_register_device(device);
>>> Applied, thanks.
>> You shouldn't have. This patch means exynos5540 has no cpuidle driver at
>> all. It should be fixed in the Kconfig to unselect CONFIG_CPU_IDLE for
>> an exynos5540.
> To shed more light on this, let me add that you need to register a cpuidle
> driver only if you have more states than a simple WFI or you need some
> crazy steps to enter WFI. Default setup falls back to generic ARM WFI.
> (Daniel, do we get the nice idle stats as provided by cpuidle core then?)
Nope, but with one state, idle vs busy stats do the trick.
BTW, I am writing a tool to do some stats based on the idle events .
It is still at a very early development stage but we can get some
> Anyway, Exynos cpuidle is using an initcall to initialize and we support
> multiple Exynos SoCs in single zImage, so deselecting CONFIG_CPU_IDLE is
> not an option.
> Considering multiplatform requirements, the driver has to
> be modified to initialize only on supported platforms, either by:
> a) dropping the initcall and calling the init function directly from
> b) checking if machine we are running on is supported, which would mean a
> long list of all Exynos SoCs that needs to be checked.
> An evolution of option a) is registering a platform device somewhere in
> arch/arm/mach-exynos and making exynos-cpuidle a platform driver.
Yes, I am favorable to this solution .
> problem is that you must register a static platform device from arch code,
> because cpuidle is not a real hardware block that can be put into device
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