linux-kernel - Re: [PATCH v2 -next] powerpc: kernel/time.c

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Message-ID: <bd93a018-ad72-bff3-e7f9-f1396f770465@huawei.com>
Date:   Wed, 24 Mar 2021 16:29:45 +0800
From:   "heying (H)" <heying24@...wei.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
CC:     <mpe@...erman.id.au>, <benh@...nel.crashing.org>,
        <paulus@...ba.org>, <a.zummo@...ertech.it>, <npiggin@...il.com>,
        <msuchanek@...e.de>, <tglx@...utronix.de>, <peterz@...radead.org>,
        <geert+renesas@...der.be>, <kernelfans@...il.com>,
        <frederic@...nel.org>, <linuxppc-dev@...ts.ozlabs.org>,
        <linux-kernel@...r.kernel.org>, <linux-rtc@...r.kernel.org>
Subject: Re: [PATCH v2 -next] powerpc: kernel/time.c - cleanup warnings

Dear,


在 2021/3/24 14:22, Christophe Leroy 写道:
>
>
> Le 24/03/2021 à 07:14, Christophe Leroy a écrit :
>>
>>
>> Le 24/03/2021 à 00:05, Alexandre Belloni a écrit :
>>> On 23/03/2021 23:18:17+0100, Alexandre Belloni wrote:
>>>> Hello,
>>>>
>>>> On 23/03/2021 05:12:57-0400, He Ying wrote:
>>>>> We found these warnings in arch/powerpc/kernel/time.c as follows:
>>>>> warning: symbol 'decrementer_max' was not declared. Should it be 
>>>>> static?
>>>>> warning: symbol 'rtc_lock' was not declared. Should it be static?
>>>>> warning: symbol 'dtl_consumer' was not declared. Should it be static?
>>>>>
>>>>> Declare 'decrementer_max' and 'rtc_lock' in powerpc asm/time.h.
>>>>> Rename 'rtc_lock' in drviers/rtc/rtc-vr41xx.c to 'vr41xx_rtc_lock' to
>>>>> avoid the conflict with the variable in powerpc asm/time.h.
>>>>> Move 'dtl_consumer' definition behind "include <asm/dtl.h>" 
>>>>> because it
>>>>> is declared there.
>>>>>
>>>>> Reported-by: Hulk Robot <hulkci@...wei.com>
>>>>> Signed-off-by: He Ying <heying24@...wei.com>
>>>>> ---
>>>>> v2:
>>>>> - Instead of including linux/mc146818rtc.h in powerpc 
>>>>> kernel/time.c, declare
>>>>>    rtc_lock in powerpc asm/time.h.
>>>>>
>>>>
>>>> V1 was actually the correct thing to do. rtc_lock is there exactly
>>>> because chrp and maple are using mc146818 compatible RTCs. This is 
>>>> then
>>>> useful because then drivers/char/nvram.c is enabled. The proper fix
>>>> would be to scrap all of that and use rtc-cmos for those platforms as
>>>> this drives the RTC properly and exposes the NVRAM for the mc146818.
>>>>
>>>> Or at least, if there are no users for the char/nvram driver on those
>>>> two platforms, remove the spinlock and stop enabling CONFIG_NVRAM or
>>>> more likely rename the symbol as it seems to be abused by both chrp 
>>>> and
>>>> powermac.
>>>>
>>>
>>> Ok so rtc_lock is not even used by the char/nvram.c driver as it is
>>> completely compiled out.
>>>
>>> I guess it is fine having it move to the individual platform as looking
>>> very quickly at the Kconfig, it is not possible to select both
>>> simultaneously. Tentative patch:
>>>
>>
>> Looking at it once more, it looks like including linux/mc146818rtc.h 
>> is the thing to do, at least for now. Several platforms are defining 
>> the rtc_lock exactly the same way as powerpc does, and including 
>> mc146818rtc.h
>>
>> I think that to get it clean, this change should go in a dedicated 
>> patch and do a bit more and explain exactly what is being do and why. 
>> I'll try to draft something for it.
>>
>> He Y., can you make a version v3 of your patch excluding the rtc_lock 
>> change ?
>>
>
> Finally, I think there is not enough changes to justify a separate patch.
>
> So you can send a V3 based on your V1. In addition to the changes you 
> had in V1, please remove the declaration of rfc_lock in 
> arch/powerpc/platforms/chrp/chrp.h

So glad to hear that. I'll do that and send my V3.


Thanks.