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SubjectRe: [PATCH v6 2/2] clocksource: Ingenic: Add support for the Ingenic X1000 OST.
Hi Zhou,

Le sam. 18 juil. 2020 à 21:42, Zhou Yanjie <zhouyanjie@wanyeetech.com>
a écrit :
> Hello Paul and Daniel,
>
> 在 2020/7/18 下午9:12, Paul Cercueil 写道:
>> Hi Daniel,
>>
>> Le ven. 17 juil. 2020 à 10:02, Daniel Lezcano
>> <daniel.lezcano@linaro.org> a écrit :
>>> On 17/07/2020 08:13, Zhou Yanjie wrote:
>>>> Hi Daniel,
>>>>
>>>> 在 2020/7/17 下午12:20, Daniel Lezcano 写道:
>>>>> On 10/07/2020 19:02, 周琰杰 (Zhou Yanjie) wrote:
>>>>>> X1000 and SoCs after X1000 (such as X1500 and X1830) had a
>>>>>> separate
>>>>>> OST, it no longer belongs to TCU. This driver will register
>>>>>> both a
>>>>>> clocksource and a sched_clock to the system.
>>>>>>
>>>>>> Tested-by: 周正 (Zhou Zheng) <sernia.zhou@foxmail.com>
>>>>>> Co-developed-by: 漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>
>>>>>> Signed-off-by: 漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>
>>>>>> Signed-off-by: 周琰杰 (Zhou Yanjie)
>>>>>> <zhouyanjie@wanyeetech.com>
>>>>>> Reviewed-by: Paul Cercueil <paul@crapouillou.net>
>>>>>> ---
>>>>>>
>>>>>> Notes:
>>>>>> v1->v2:
>>>>>> Fix compile warnings.
>>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>>> v2->v3:
>>>>>> No change.
>>>>>> v3->v4:
>>>>>> 1.Rename "ost" to "sysost"
>>>>>> 1.Remove unrelated changes.
>>>>>> 2.Remove ost_clock_parent enum.
>>>>>> 3.Remove
>>>>>> ost->percpu_timer_channel/ost->global_timer_channel.
>>>>>> 4.Set up independent .recalc_rate/.set_rate for
>>>>>> percpu/global
>>>>>> timer.
>>>>>> 5.No longer call functions in variable declarations.
>>>>>> v4->v5:
>>>>>> Use "of_io_request_and_map()" instead "of_iomap()".
>>>>>> Suggested-by: Paul Cercueil <paul@crapouillou.net>
>>>>>> v5->v6:
>>>>>> No change.
>>>>>>
>>>>>> drivers/clocksource/Kconfig | 11 +
>>>>>> drivers/clocksource/Makefile | 1 +
>>>>>> drivers/clocksource/ingenic-sysost.c | 539
>>>>>> +++++++++++++++++++++++++++++++++++
>>>>>> 3 files changed, 551 insertions(+)
>>>>>> create mode 100644 drivers/clocksource/ingenic-sysost.c
>>>>>>
>>>>>> diff --git a/drivers/clocksource/Kconfig
>>>>>> b/drivers/clocksource/Kconfig
>>>>>> index 91418381fcd4..1bca8b8fb30f 100644
>>>>>> --- a/drivers/clocksource/Kconfig
>>>>>> +++ b/drivers/clocksource/Kconfig
>>>>>> @@ -696,6 +696,17 @@ config INGENIC_TIMER
>>>>>> help
>>>>>> Support for the timer/counter unit of the Ingenic JZ
>>>>>> SoCs.
>>>>>> +config INGENIC_SYSOST
>>>>>> + bool "Clocksource/timer using the SYSOST in Ingenic X SoCs"
>>>>> We usually use silent options and let the platform's Kconfig
>>>>> enable it.
>>>>> We show up the option only when COMPILE_TEST is enabled.
>>>>>
>>>>> Is there a reason to do it differently?
>>>>
>>>>
>>>> Do you mean
>>>>
>>>> bool "Clocksource/timer using the SYSOST in Ingenic X SoCs"
>>>>
>>>> or
>>>>
>>>> default MACH_INGENIC ?
>>>
>>> Both, no default here.
>>>
>>> eg.
>>>
>>> bool "Clocksource/timer using the SYSOST in Ingenic X SoCs" if
>>> COMPILE_TEST
>>>
>>> and
>>>
>>> in arch/mips/Kconfig in the config MACH_INGENIC section :
>>>
>>> ...
>>> select INGENIC_SYSOST
>>> ...
>>
>> Disagreed. That's not how we do things on MIPS. Selecting
>> MACH_INGENIC means "this kernel will support Ingenic SoCs", but not
>> that it will only support these. Hence the depends on MIPS /
>> default MACH_INGENIC.
>>
>> As for the select INGENIC_SYSOST, this driver only applies to a few
>> SoCs, I certainly don't want it to be force-enabled. I don't even
>> wait it to be force-enabled on X1000, since it is optional there
>> too.
>>
>> Cheers,
>> -Paul
>
>
> If we still need to keep the "default MACH_INGENIC", then Daniel can
> directly apply the v6 version.
>
> If we need to use the silent options, maybe we can enable them
> separately according to
> MACH_JZ4740/MACH_JZ4770/MACH_JZ4780/MACH_X1000/MACH_X1830.
>
> In fact, I think X1000 and X1830 need to enable this driver in most
> cases, because the current test has found that use TCU to provide
> clocksource and clockevent will cause data loss/error when
> transmitting data through spi or ethernet. And these errors no longer
> appear after using OST.

This is likely because the clock is too fast, try to reduce it by a
factor 2 or 4, it should behave better.

If it turns out OST is really needed, then it should be selected from
MACH_X1000/X1830, not MACH_INGENIC.

Cheers,
-Paul

> Thanks and best regards!
>
>
>>
>>>
>>>> This driver has some origins from "INGENIC_TIMER" driver and
>>>> "INGENIC_OST" driver.
>>>> Early Ingenic processors used TCU (timer/counter unit, has 6 or 8
>>>> generic timer channels) to provide clocksource and clockevent
>>>> (both with
>>>> only 16bit precision). This part of the processor can only use
>>>> "INGENIC_TIMER" driver.
>>>>
>>>> Later processors provide an independent 32bit or 64bit timer
>>>> channel
>>>> (still under TCU, known as ost channel, this channel can not
>>>> generate
>>>> interrupt) to provid higher precision clocksource. The
>>>> "INGENIC_OST"
>>>> driver is for this channel. These processors can use
>>>> "INGENIC_TIMER"
>>>> driver, but using "INGENIC_OST" driver to provide higher precision
>>>> clocksource would be a better choice (clockevent still needs to be
>>>> provided by generic timer channel of TCU, and still 16bit
>>>> precision).
>>>>
>>>> And the recent processors provide a SYSOST components, it is
>>>> independent
>>>> from TCU, including a 64bit timer channel for clocksource and a
>>>> 32bit
>>>> timer channel for clockevent. Although these processors can also
>>>> use
>>>> "INGENIC_TIMER" driver, but the better choice is completely
>>>> independent
>>>> use of "INGENIC_SYSOST" driver to provide higher precision
>>>> clocksource
>>>> and clockevent.
>>>
>>> Ok, the rating should do the job then.
>>>
>>> Thanks for the explanation.
>>>
>>>> You may have already noticed that this independent SYSOST
>>>> component is
>>>> like an upgraded and streamlined TCU, which only retains one
>>>> generic
>>>> timer channel that can generate interrupts, upgrade it from 16bit
>>>> to
>>>> 32bit, and then retain the 64bit ost channel. so the driver code
>>>> and
>>>> Kconfig code of this patch is largely referenced
>>>> "INGENIC_TIMER" driver and "INGENIC_OST" driver.
>>>>
>>>> Thanks and best regards!
>>>>
>>>>>> + default MACH_INGENIC
>>>>>> + depends on MIPS || COMPILE_TEST
>>>>>> + depends on COMMON_CLK
>>>>>> + select MFD_SYSCON
>>>>>> + select TIMER_OF
>>>>>> + select IRQ_DOMAIN
>>>>>> + help
>>>>>> + Support for the SYSOST of the Ingenic X Series SoCs.
>>>>>> +
>>>>> [ ... ]
>>>>>
>>>>>
>>>
>>>
>>> --
>>> <http://www.linaro.org/> Linaro.org │ Open source software for
>>> ARM SoCs
>>>
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>>

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