Message-ID: <096c8788-3c50-3eae-1c8e-c0c7487b00af@wanyeetech.com>
Date:   Sat, 18 Jul 2020 21:42:26 +0800
From:   Zhou Yanjie <zhouyanjie@...yeetech.com>
To:     Paul Cercueil <paul@...pouillou.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        robh+dt@...nel.org, tglx@...utronix.de, dongsheng.qiu@...enic.com,
        aric.pzqi@...enic.com, rick.tyliu@...enic.com,
        yanfei.li@...enic.com, sernia.zhou@...mail.com,
        zhenwenjin@...il.com
Subject: Re: [PATCH v6 2/2] clocksource: Ingenic: Add support for the Ingenic
 X1000 OST.

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@...aro.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@...mail.com>
>>>>>  Co-developed-by: 漆鹏振 (Qi Pengzhen) <aric.pzqi@...enic.com>
>>>>>  Signed-off-by: 漆鹏振 (Qi Pengzhen) <aric.pzqi@...enic.com>
>>>>>  Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@...yeetech.com>
>>>>>  Reviewed-by: Paul Cercueil <paul@...pouillou.net>
>>>>>  ---
>>>>>
>>>>>  Notes:
>>>>>       v1->v2:
>>>>>       Fix compile warnings.
>>>>>       Reported-by: kernel test robot <lkp@...el.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@...pouillou.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.

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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