[PATCH 0/4] cpufreq: use generic cpufreq drivers for Exynos5250 platform

[linux.amoon@gmail.com (Anand Moon)]

On 15 May 2015 at 23:18, Javier Martinez Canillas
<javier.martinez@collabora.co.uk> wrote:
> Hello Bartlomiej,
>
> On 04/22/2015 07:37 PM, Bartlomiej Zolnierkiewicz wrote:
>>
>> On Tuesday, April 21, 2015 04:45:56 PM Kevin Hilman wrote:
>>> Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> writes:
>>>
>>> > On Monday, April 20, 2015 02:07:33 PM Kevin Hilman wrote:
>>> >> Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> writes:
>>> >>
>>> >> > Hi,
>>> >> >
>>> >> > This patch series removes the use of Exynos5250 specific support
>>> >> > from exynos-cpufreq driver and enables the use of cpufreq-dt driver
>>> >> > for this platform.  The exynos-cpufreq driver itself is also removed
>>> >> > as it is no longer used/needed after Exynos5250 support removal.
>>> >> >
>>> >> > This patch series has been tested on Exynos5250 based Arndale board.
>>> >> >
>>> >> > Depends on:
>>> >> > - next-20150330 branch of linux-next kernel tree
>>> >> > - "[PATCH 0/6] cpufreq: use generic cpufreq drivers for Exynos4210
>>> >> >   platform" [1]
>>> >> > - "[PATCH 0/6] cpufreq: use generic cpufreq drivers for Exynos4x12
>>> >> >   platform" [2]
>>> >> > - "[PATCH] cpufreq: exynos: remove dead ->need_apll_change method" [3]
>>> >>
>>> >> Any chance you could prepare a branch with all the dependencies for easy
>>> >> testing?
>>> >
>>> > All cpufreq changes with needed dependencies are now availble in
>>> >
>>> >     https://github.com/bzolnier/linux.git
>>> >
>>> > repository and the branch is
>>> >
>>> >     next-20150330-generic-cpufreq-exynos5420-5800-v2
>>>
>>> Great, thanks.
>>>
>>> >> Also, The previous version from Thomas was v12, and this one is neither
>>> >> versioned nor has any reference to what may have changed since that
>>> >
>>> > Please note that Thomas' patchset was split on separate parts (this is
>>> > part #3) and heavily modified so the previous versioning was dropped.
>>> >
>>> > The cover letter of part #1 ("[PATCH 0/6] cpufreq: use generic cpufreq
>>> > drivers for Exynos4210 platform") contains detailed changelog on what has
>>> > been changed since Thomas' original v12 patch series.  Individual Thomas'
>>> > patches which were modified by me also contain such information.
>>> >
>>> > Part #2 ("[PATCH 0/6] cpufreq: use generic cpufreq drivers for Exynos4x12
>>> > platform") was entirely new code when compared to Thomas' v12 patchset so
>>> > its cover letter doesn't contain such detailed changelog as part #1.
>>> >
>>> > The newly posted part #4 ("[PATCH 0/8] cpufreq: add generic cpufreq driver
>>> > support for Exynos5250/5800 platforms" https://lkml.org/lkml/2015/4/21/314)
>>> > also contains the detailed changelog.
>>> >
>>> > However for part #3 (this one, "[PATCH 0/4] cpufreq: use generic cpufreq
>>> > drivers for Exynos5250 platform") such summary changelog got missed for
>>> > some reason.  Here it is:
>>> > - split Exynos5250 support from the original patch
>>> > - moved E5250_CPU_DIV[0,1]() macros to clk-exynos5250.c
>>> > - added CPU regulator supply property for Google Spring board
>>> > - removed exynos-cpufreq driver entirely as it is no longer used/needed
>>>
>>> Great, thanks for clarifying.
>>>
>>> >> version.  Also, on v12, I had several comments[1] and wonder if they've
>>> >> been addressed.
>>> >
>>> > All issues previously reported should have been fixed.  If you still see
>>> > some problems please let me know.
>>> >
>>> > [ I see now that exynos5420-arndale-octa.dts, exynos5420-peach-pit.dts,
>>> >   exynos5420-smdk5420.dts and exynos5800-peach-pi.dts should also have
>>> >   been updated to contain CPU cluster regulator supply properties or else
>>> >   if the default vdd_arm/vdd_kfc regulator state is set to too low value
>>> >   there may be problems with stability when switching to higher than
>>> >   default frequencies.  I have posted v2 version of patch #2/8 of part #4
>>> >   and pushed v2 combined branch on github.  Sorry for the inconvenience. ]
>>>
>>> I've now tested your v2 branch with the bL switcher disabled, CPUidle
>>> enabled and CPUfreq enabled.
>>>
>>> With the default governor set to performance, it fails to boot.  The last
>>> kernel messages on the console are:
>>
>> [ Small explanation for people not following the discussion from
>>   the start:
>>
>>   This testing is relevant to part #4 of the rework: "[PATCH 0/8]
>>   cpufreq: add generic cpufreq driver support for Exynos5250/5800
>>   platforms" (https://lkml.org/lkml/2015/4/21/314"), not this one
>>   which is part #3 and has no known issues. ]
>>
>
> I know that Exynos5420/5422/5800 is related to part #4 and not #3 but I
> wanted to answer in this thread since here is where Kevin reported the
> issue. I tried your next-20150330-generic-cpufreq-exynos5420-5800-v2-debug
> branch with exynos_defconfig plus CONFIG_BL_SWITCHER disabled and:
>
> CONFIG_ARM_BIG_LITTLE_CPUFREQ=y
> CONFIG_ARM_DT_BL_CPUFREQ=y
>
> By default CONFIG_CPU_FREQ_GOV_PERFORMANCE=y but with that option it fails
> to boot as well on my Exynos5420 Peach Pit so seems to be exactly what Kevin
> reported on the Exynos5800 Peach Pi Chromebook.
>
>>> [...]
>>> [    3.426021] cpu cpu0: bL_cpufreq_init: CPU 0 initialized
>>> [    3.431189] cpu cpu4: bL_cpufreq_init: CPU 4 initialized
>>>
>>> However, with the default governor set to userspace it boots fine until
>>> my userspace (ubuntu) tries to enable the ondemand governor, and then it
>>> hangs.
>>>
>>> For it to boot, I have to disable the ondemand governor, and set the
>>> default governor to userspace.
>
> Disabling CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE and the performance
> governor and enabling the userpace governor and setting it as default
> makes the kernel to boot again which is the same behaviour Kevin had.
>
> Also I can see that the CPUS have a cpufreq and the scaling driver
> is the arm b.L one:
>
> # cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver
> arm-big-little
> arm-big-little
> arm-big-little
> arm-big-little
> arm-big-little
> arm-big-little
> arm-big-little
> arm-big-little
>
>>
>> I've tried with ARM big.LITTLE cpuidle support enabled (I've just noticed
>> that it is not turned on in exynos_defconfig) and my ODROID-XU3 board
>> fails to boot.  This happens even with cpufreq support disabled (hard
>> lockup happens during mmc initialization which is done just after cpufreq
>> initialization).
>>
>> Could you please check if disabling cpuidle support helps?
>
> I don't have CPUIdle enabled since as you said is not turned on in exynos
> defconfig by default so I think that is just a red herring.
>
>>
>>> As I reported earlier on Thomas' series, I suspect this is related to
>>> the fact that the higher OPPs aren't really functional without voltage
>>> scaling also supported.
>>
>> Part #4 contains voltage scaling support for arm_big_little[_dt] driver
>> so this should not be a problem any longer.
>>
>> You may try next-20150330-generic-cpufreq-exynos5420-5800-v2-debug
>> branch from my github (with cpufreq debugging printks enabled) to check
>> whether the voltage scaling is indeed done on your board.
>>
>
> The last boot log shown on the serial console with your debug branch is:
>
> [    3.078885] cpu cpu0: _get_cluster_clk_and_freq_table: clk: ee516a80 & freq table: ee511540, cluster: 0
> [    3.088128] cpu cpu0: bL_cpufreq_init: CPU 0 physical_cluster 0
> [    3.094024] cpu cpu0: bL_cpufreq_init: CPU 1 physical_cluster 0
> [    3.099912] cpu cpu0: bL_cpufreq_init: CPU 2 physical_cluster 0
> [    3.105871] cpu cpu0: bL_cpufreq_init: CPU 3 physical_cluster 0
> [    3.111710] cpu cpu0: bL_cpufreq_init: CPU 0 initialized
> [    3.117291] cpu cpu4: _get_cluster_clk_and_freq_table: clk: ee516d80 & freq table: ee50c180, cluster: 1
> [    3.126379] cpu cpu4: bL_cpufreq_init: CPU 4 physical_cluster 1
> [    3.132276] cpu cpu4: bL_cpufreq_init: CPU 5 physical_cluster 1
> [    3.138169] cpu cpu4: bL_cpufreq_init: CPU 6 physical_cluster 1
> [    3.144069] cpu cpu4: bL_cpufreq_init: CPU 7 physical_cluster 1
> [    3.149967] cpu cpu4: bL_cpufreq_init: CPU 4 initialized
> [    3.155453] arm_big_little: bL_cpufreq_set_rate: cpu: 4, old cluster: 1, new cluster: 1, freq: 1300000
> [    3.164551] arm_big_little: bL_cpufreq_set_rate_cluster: cpu 4, cluster: 1, 600 MHz, -1 mV --> 1300 MHz, -1 mV
> [    3.174646] arm_big_little: bL_cpufreq_register: Registered platform driver: dt-bl
> [    3.182305] Unable to handle kernel paging request at virtual address 60000186
>
> so it seems to be a bug in the code and not about OPPs not functional due
> voltage scaling not working as Kevin guessed.
>
> However, as Kevin mentioned is strange that the regulator voltages are -1
> as you can see in the above boot log.
>
> Also when setting a scaling_setspeed to one of the scaling available
> frequencies for a given CPU, I see in the log that the frequency is
> scaled for all the cluster and correctly reported in scaling_cur_freq
> but the scaled voltage is always reported as -1 again:
>
> [  899.002840] arm_big_little: bL_cpufreq_set_rate_cluster: cpu 0, cluster: 0, 1800 MHz, -1 mV --> 1100 MHz, -1 mV
> [  946.153852] arm_big_little: bL_cpufreq_set_rate: cpu: 0, old cluster: 0, new cluster: 0, freq: 1200000
> [  946.161785] arm_big_little: bL_cpufreq_set_rate_cluster: cpu 0, cluster: 0, 1100 MHz, -1 mV --> 1200 MHz, -1 mV
> [  975.328748] arm_big_little: bL_cpufreq_set_rate: cpu: 4, old cluster: 1, new cluster: 1, freq: 1200000
> [  975.336663] arm_big_little: bL_cpufreq_set_rate_cluster: cpu 4, cluster: 1, 600 MHz, -1 mV --> 1200 MHz, -1 mV
>
>>> I'm also seeing the wait_until_divider_stable errors when switching
>>> between the available A7 OPPs.  I'd reported this one earlier as well,
>>> along with the script to reproduce it.
>>
>> I've tried your script and it works fine for me (I only needed to change
>> cpu4 to cpu0 as on ODROID-XU3 CPUs 0,5,6,7 are A7 and 1,2,3,4 are A15).
>>
>> Best regards,
>> --
>> Bartlomiej Zolnierkiewicz
>> Samsung R&D Institute Poland
>> Samsung Electronics
>>
>
> Best regards,
> Javier

Hi Javier/Bartlomiej,

Below patch helps debug this problem.

http://article.gmane.org/gmane.linux.power-management.general/58549/match=cpufreq+arm_big_little+check+if+frequency+set+correctly

-Anand Moon

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