Subject: [PATCH] Exynos4: cpuidle: support dual CPUs with AFTR state

From: [email-masked] (Daniel Lezcano)
Date: Fri, 15 Aug 2014 01:57:02 +0200

On 08/14/2014 12:55 PM, Bartlomiej Zolnierkiewicz wrote:
>
> Hi,
>
> On Monday, July 21, 2014 01:06:32 PM Daniel Lezcano wrote:
>> On 07/16/2014 07:34 PM, Bartlomiej Zolnierkiewicz wrote:
>>>
>>> Hi,
>>>
>>> On Friday, May 30, 2014 03:53:09 PM Bartlomiej Zolnierkiewicz wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Friday, May 30, 2014 01:34:45 PM Tomasz Figa wrote:
>>>>> Hi Daniel,
>>>>>
>>>>> On 30.05.2014 11:30, Daniel Lezcano wrote:
>>>>>> On 04/24/2014 07:42 PM, Tomasz Figa wrote:
>>>>>>> Hi Daniel,
>>>>>>>
>>>>>>> Please see my comments inline.
>>>>>>>
>>>>>>> Btw. Please fix your e-mail composer to properly wrap your messages
>>>>>>> around 7xth column, as otherwise they're hard to read.
>>>>>>>
>>>>>>> On 04.04.2014 11:48, Daniel Lezcano wrote:
>>>>>>>> The following driver is for exynos4210. I did not yet finished the
>>>>>>>> other boards, so
>>>>>>>> I created a specific driver for 4210 which could be merged later.
>>>>>>>>
>>>>>>>> The driver is based on Colin Cross's driver found at:
>>>>>>>>
>>>>>>>> https://android.googlesource.com/kernel/exynos/+/e686b1ec67423c40b4fdf811f9a4dfa3b393a010%5E%5E!/
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> This one was based on a 3.4 kernel and an old API.
>>>>>>>>
>>>>>>>> It has been refreshed, simplified and based on the recent code cleanup
>>>>>>>> I sent
>>>>>>>> today.
>>>>>>>>
>>>>>>>> The AFTR could be entered when all the cpus (except cpu0) are down. In
>>>>>>>> order to
>>>>>>>> reach this situation, the couple idle states are used.
>>>>>>>>
>>>>>>>> There is a sync barrier at the entry and the exit of the low power
>>>>>>>> function. So
>>>>>>>> all cpus will enter and exit the function at the same time.
>>>>>>>>
>>>>>>>> At this point, CPU0 knows the other cpu will power down itself. CPU0
>>>>>>>> waits for
>>>>>>>> the CPU1 to be powered down and then initiate the AFTR power down
>>>>>>>> sequence.
>>>>>>>>
>>>>>>>> No interrupts are handled by CPU1, this is why we switch to the timer
>>>>>>>> broadcast
>>>>>>>> even if the local timer is not impacted by the idle state.
>>>>>>>>
>>>>>>>> When CPU0 wakes up, it powers up CPU1 and waits for it to boot. Then
>>>>>>>> they both
>>>>>>>> exit the idle function.
>>>>>>>>
>>>>>>>> This driver allows the exynos4210 to have the same power consumption
>>>>>>>> at idle
>>>>>>>> time than the one when we have to unplug CPU1 in order to let CPU0 to
>>>>>>>> reach
>>>>>>>> the AFTR state.
>>>>>>>>
>>>>>>>> This patch is a RFC because, we have to find a way to remove the macros
>>>>>>>> definitions and cpu powerdown function without pulling the arch
>>>>>>>> dependent
>>>>>>>> headers.
>>>>>>>>
>>>>>>>> Signed-off-by: Daniel Lezcano <[email-masked]>
>>>>>>>> ---
>>>>>>>>     arch/arm/mach-exynos/common.c        |   11 +-
>>>>>>>>     drivers/cpuidle/Kconfig.arm          |    8 ++
>>>>>>>>     drivers/cpuidle/Makefile             |    1 +
>>>>>>>>     drivers/cpuidle/cpuidle-exynos4210.c |  226
>>>>>>>> ++++++++++++++++++++++++++++++++++
>>>>>>
>>>>>> [ ... ]
>>>>>>
>>>>>>
>>>>>>> Otherwise, I quite like the whole idea. I need to play a bit with CPU
>>>>>>> hotplug and PMU to verify that things couldn't really be simplified a
>>>>>>> bit, but in general this looks reasonably.
>>>>>>
>>>>>> Hi Tomasz,
>>>>>>
>>>>>> did you have time to look at this simplification ?
>>>>>
>>>>> Unfortunately I got preempted with other things to do and now I'm on
>>>>> vacation. I worked a bit with Bart (added on CC) on this and generally
>>>>> the conclusion was that all the things are necessary. He was also
>>>>> working to extend the driver to support Exynos4x12.
>>>>>
>>>>> Bart, has anything interesting showed up since we talked about this last
>>>>> time?
>>>>
>>>> Since we last looked into this I have fixed the "standard" AFTR support
>>>> for Exynos3250 and started to work on adding Exynos3250 support to this
>>>> driver (as Exynos3250 support has bigger priority than Exynos4x12 one).
>>>> Unfortunately I also got preempted with other things so it is still
>>>> unfinished and doesn't work yet.  Moreover I had no possibility to test
>>>> the new driver on Exynos4210 based Origen yet (I hope to do this next
>>>> week).
>>>
>>> I have tested this patch on Origen board (Exynos4210 rev 1.1) and it
>>> causes system lockup (it seems that the code gets stuck on waiting for
>>> CPU1 to wake up).
>>>
>>> The kernels I have tried:
>>> * current -next + this patch + few fixes to bring it up to date
>>> * commit cd245f5 + this patch + some fixes
>>> * next-20140403 + your Exynos cpuidle patch series + this patch
>>>
>>> I have also tried with S5P_VA_SYSRAM replaced by S5P_INFORM5 to
>>> match Exynos 4210 rev 1.1 but it didn't help.
>>>
>>> U-Boot version used is:
>>> U-Boot 2012.07 (Sep 22 2012 - 05:12:41) for ORIGEN
>>>
>>> Could you please tell me which hardware/bootloader/kernel exactly
>>> have you used to test this patch?
>>
>> When I used it, it was on top of 3.15-rc1:
>>
>> https://git.linaro.org/people/daniel.lezcano/linux.git/shortlog/refs/heads/cpuidle/samsung-next
>>
>> The hardware was a exynos-4210 origen board ver A.
>
> I need the following patch to make this driver work on my hardware.

Thanks for the patch !

> [ Unfortunately even with this patch the driver doesn't work reliably.
>    After 30-40 minutes of stress testing it lockups the system (I can
>    send you testing app+script if needed). ]

Yes, please. I will try to reproduce it.

> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
>
>
> From: Bartlomiej Zolnierkiewicz <[email-masked]>
> Subject: [PATCH] cpuidle: Exynos4210: make coupled driver work on Revision 1.1
>
> * Add static inline helper cpu_boot_reg_base() and use it instead of
>    BOOT_VECTOR macro.
>
> * Use S5P_INFORM register instead of S5P_VA_SYSRAM one on Revison 1.1
>    (this matches platform code in arch/arm/mach-exynos/platsmp.c).
>
> * Retry poking CPU1 out of the BOOT ROM if necessary
>    (this matches platform code in arch/arm/mach-exynos/platsmp.c).
>
> Signed-off-by: Bartlomiej Zolnierkiewicz <[email-masked]>
> Acked-by: Kyungmin Park <[email-masked]>
> ---
>   drivers/cpuidle/cpuidle-exynos4210.c |   27 ++++++++++++++-------------
>   1 file changed, 14 insertions(+), 13 deletions(-)
>
> Index: b/drivers/cpuidle/cpuidle-exynos4210.c
> ===================================================================
> --- a/drivers/cpuidle/cpuidle-exynos4210.c	2014-07-22 15:42:11.580365939 +0200
> +++ b/drivers/cpuidle/cpuidle-exynos4210.c	2014-07-22 16:11:01.112369130 +0200
> @@ -29,12 +29,19 @@
>   static atomic_t exynos_idle_barrier;
>   static atomic_t cpu1_wakeup = ATOMIC_INIT(0);
>
> -#define BOOT_VECTOR S5P_VA_SYSRAM
>   #define S5P_VA_PMU                  S3C_ADDR(0x02180000)
>   #define S5P_PMUREG(x)              (S5P_VA_PMU + (x))
> +#define S5P_INFORM5                 S5P_PMUREG(0x0814)
>   #define S5P_ARM_CORE1_CONFIGURATION S5P_PMUREG(0x2080)
>   #define S5P_ARM_CORE1_STATUS        S5P_PMUREG(0x2084)
>
> +static inline void __iomem *cpu_boot_reg_base(void)
> +{
> +	if (samsung_rev() == EXYNOS4210_REV_1_1)
> +		return S5P_INFORM5;
> +	return S5P_VA_SYSRAM;
> +}
> +
>   static void (*exynos_aftr)(void);
>   extern void exynos_cpu_resume(void);
>   static int cpu_suspend_finish(unsigned long flags)
> @@ -76,7 +83,7 @@ static int exynos_cpu0_enter_aftr(void)
>   			 * boot back up again, getting stuck in the
>   			 * boot rom code
>   			 */
> -			if (__raw_readl(BOOT_VECTOR) == 0)
> +			if (__raw_readl(cpu_boot_reg_base()) == 0)
>   				goto abort;
>
>   			cpu_relax();
> @@ -95,7 +102,7 @@ abort:
>   		 * Set the boot vector to something non-zero
>   		 */
>   		__raw_writel(virt_to_phys(exynos_cpu_resume),
> -			     BOOT_VECTOR);
> +			     cpu_boot_reg_base());
>   		dsb();
>
>   		/*
> @@ -108,24 +115,18 @@ abort:
>   		/*
>   		 * Wait for cpu1 to get stuck in the boot rom
>   		 */
> -		while ((__raw_readl(BOOT_VECTOR) != 0) &&
> +		while ((__raw_readl(cpu_boot_reg_base()) != 0) &&
>   		       !atomic_read(&cpu1_wakeup))
>   			cpu_relax();
>
> -		if (!atomic_read(&cpu1_wakeup)) {
> +		while (!atomic_read(&cpu1_wakeup)) {
>   			/*
>   			 * Poke cpu1 out of the boot rom
>   			 */
>   			__raw_writel(virt_to_phys(exynos_cpu_resume),
> -				     BOOT_VECTOR);
> +				     cpu_boot_reg_base());
>   			dsb_sev();
>   		}
> -
> -		/*
> -		 * Wait for cpu1 to finish booting
> -		 */
> -		while (!atomic_read(&cpu1_wakeup))
> -			cpu_relax();
>   	}
>
>   	return ret;
> @@ -165,7 +166,7 @@ static int exynos_enter_aftr(struct cpui
>   {
>   	int ret;
>
> -	__raw_writel(virt_to_phys(exynos_cpu_resume), BOOT_VECTOR);
> +	__raw_writel(virt_to_phys(exynos_cpu_resume), cpu_boot_reg_base());
>
>   	/*
>   	 * Waiting all cpus to reach this point at the same moment
>
>
>

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