linux-kernel - Re: [PATCH] ARM: exynos_defconfig: Enable big.LITTLE CPUidle support

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Message-ID: <CABxcv=nwXc-_Y7qdZ56EGxM266Yifm56m6+Pb8iTHSWLHHSkfA@mail.gmail.com>
Date:	Sat, 29 Aug 2015 12:07:45 +0200
From:	Javier Martinez Canillas <javier@...hile0.org>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Javier Martinez Canillas <javier@....samsung.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Kukjin Kim <kgene@...nel.org>,
	Thierry Reding <treding@...dia.com>,
	Anand Moon <linux.amoon@...il.com>,
	Russell King <linux@....linux.org.uk>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	Sjoerd Simons <sjoerd.simons@...labora.co.uk>,
	Lukasz Majewski <l.majewski@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ARM: exynos_defconfig: Enable big.LITTLE CPUidle support

Hello Krzysztof,

On Sat, Aug 29, 2015 at 11:55 AM, Krzysztof Kozlowski
<k.kozlowski@...sung.com> wrote:
> 2015-08-29 18:33 GMT+09:00 Javier Martinez Canillas <javier@....samsung.com>:
>> Hello Krzysztof,
>>
>> On 08/29/2015 11:01 AM, Krzysztof Kozlowski wrote:
>>> W dniu 28.08.2015 o 17:16, Javier Martinez Canillas pisze:
>>>> Some Exynos big.LITTLE boards (i.e: Exynos5420 and Exynos5800 based
>>>> Chromebooks) have proper firmware that allow the big.LITTLE CPUidle
>>>> driver to work correctly, so enable support for this.
>>>>
>>>> Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>
>>>>
>>>> ---
>>>> Kukjin and Krzysztof,
>>>>
>>>> As you know there are other boards like the Exynos5422 based Odroid XU{3,4}
>>>> whose firmware is broken due leaving CCI in secure mode which means that the
>>>> kernel MCPM support can't properly manage CCI.
>>>>
>>>> So if you pick this patch, it should be tested in kernelci before appearing
>>>> in linux-next to prevent any boot issues.
>>>>
>>>> But if that happens, I believe that is better to do a fix / workaround in
>>>> those broken platforms since nothing prevents users to enable this option
>>>> anyways. For example the CCI device node could be disabled in the DTS.
>>>>
>>>>  arch/arm/configs/exynos_defconfig | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>
>>> On Odroid XU3L (next-20150828, Hardkernel u-boot) boot hangs just after:
>>>
>>
>> Thanks for testing, I was expecting that is just that I don't have a
>> Odroid XU{3,4} board for test here, I guess I should get one.
>>
>>> [    2.568650] dwmmc_exynos 12200000.mmc: num-slots property not found,
>>> assuming 1 slot is available
>>>
>>> ... so no. NACK :). First the boards, firmware, bootloader or kernel
>>
>> Agreed with the nack :)
>>
>>> code have to be fixed.
>>>
>>
>> Or disable CCI, could you please test the following patch [0] so I
>> can post it properly?
>
> It fixes the boot hang but causes other issues. Not all CPUs boot (I

Thanks for testing.

> tested it on Chanho Park's patch for fixing CPU boot with SWRESET):
> [    0.010781] CPU0: update cpu_capacity 448
> [    0.010839] CPU0: thread -1, cpu 0, socket 1, mpidr 80000100
> [    0.011098] Setting up static identity map for 0x40008280 - 0x400082d8
> [    0.056329] CPU1: update cpu_capacity 448
> [    0.056337] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
> [    0.071100] CPU2: update cpu_capacity 448
> [    0.071107] CPU2: thread -1, cpu 2, socket 0, mpidr 80000002
> [    0.086103] CPU3: update cpu_capacity 448
> [    0.086111] CPU3: thread -1, cpu 3, socket 0, mpidr 80000003
> [    0.101100] CPU4: update cpu_capacity 1535
> [    0.101108] CPU4: thread -1, cpu 0, socket 0, mpidr 80000000
> [    1.115009] CPU5: failed to boot: -110
> [    2.130019] CPU6: failed to boot: -110
> [    3.145049] CPU7: failed to boot: -110
> [    3.145151] Brought up 5 CPUs
> [    3.145196] SMP: Total of 5 processors activated (240.00 BogoMIPS).
> [    3.145251] CPU: WARNING: CPU(s) started in wrong/inconsistent
> modes (primary CPU mode 0x13)
> [    3.145327] CPU: This may indicate a broken bootloader or firmware.
> [    3.149347] devtmpfs: initialized
>

Sigh, such an inconsistent behavior between Exynos5420/5422/5800 boards :-/

Any ideas? I agree that the b.L CPUidle support shouldn't be enabled
by default in exynos_defconfig but as I said nothing prevents the user
to enable that option and make the board to hang on boot.

> Best regards,
> Krzysztof
>

Best regards,
Javier
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