From: Jiaxun Yang <jiaxun.yang@flygoat.com>
To: Tiezhu Yang <yangtiezhu@loongson.cn>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Huacai Chen <chenhc@lemote.com>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
Xuefeng Li <lixuefeng@loongson.cn>
Subject: Re: [PATCH 1/6] MIPS: Loongson64: Do not write the read only field LPA of CP0_CONFIG3
Date: Mon, 2 Nov 2020 18:47:50 +0800 [thread overview]
Message-ID: <f901dcdc-9724-a725-87ca-afe2aa216a94@flygoat.com> (raw)
In-Reply-To: <a3e4cd0f-7500-b994-15b1-8df1cff24ab5@flygoat.com>
在 2020/10/30 20:13, Jiaxun Yang 写道:
>
>
> 在 2020/10/30 14:22, Tiezhu Yang 写道:
>> On 10/30/2020 12:00 PM, Jiaxun Yang wrote:
>>>
>>>
>>> 在 2020/10/29 16:02, Tiezhu Yang 写道:
>>>> The field LPA of CP0_CONFIG3 register is read only for Loongson64,
>>>> so the
>>>> write operations are meaningless, remove them.
>>>>
>>>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>>>> ---
>>>> arch/mips/include/asm/mach-loongson64/kernel-entry-init.h | 8
>>>> --------
>>>> arch/mips/loongson64/numa.c | 3 ---
>>>> 2 files changed, 11 deletions(-)
>>> Hi Tiezhu,
>>>
>>> AFAIK it's not read only on 3A1000.
>>> Have you check with hardware guys?
>>
>> Hi Jiaxun,
>>
>> Yes, I checked it before send this patch, the field LPA of CP0_CONFIG3
>> on 3A1000 is also read only, we can see the related description in the
>> chapter 3.22 of Loongson_3A1000_cpu_user_2.
>
> On page 36, it said:
> "能否写ELPA位依赖于Config3寄存器的LPA域 。当Config3的LPA位为0时，
> PageGrain的ELPA位被置位。"
>
> Don't know if it matters.
>
> @Huacai, Any comments? Do you know why it exists here?
Confirmed by another rev of the manual that it's only a tip for implementer.
I guess my assumption was wrong.
LPA should be read-only though.....
Thanks
- Jiaxun
>
> Thanks
>
> - Jiaxun
next prev parent reply other threads:[~2020-11-02 10:48 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-29 8:02 [PATCH 0/6] Modify some registers operations and move decode_cpucfg() to loongson_regs.h Tiezhu Yang
2020-10-29 8:02 ` [PATCH 1/6] MIPS: Loongson64: Do not write the read only field LPA of CP0_CONFIG3 Tiezhu Yang
2020-10-30 4:00 ` Jiaxun Yang
2020-10-30 6:22 ` Tiezhu Yang
2020-10-30 12:13 ` Jiaxun Yang
2020-11-02 10:47 ` Jiaxun Yang [this message]
2020-10-29 8:02 ` [PATCH 2/6] MIPS: Loongson64: Set the field ELPA of CP0_PAGEGRAIN only once Tiezhu Yang
2020-10-29 8:02 ` [PATCH 3/6] MIPS: Loongson64: Set IPI_Enable register per core by itself Tiezhu Yang
2020-10-29 8:02 ` [PATCH 4/6] MIPS: Loongson64: Add Mail_Send support for 3A4000+ CPU Tiezhu Yang
2020-10-30 4:06 ` Jiaxun Yang
2020-10-30 6:37 ` Tiezhu Yang
2020-10-29 8:03 ` [PATCH 5/6] MIPS: Loongson64: Make sure the PC address is correct when 3A4000+ CPU hotplug Tiezhu Yang
2020-10-29 8:03 ` [PATCH 6/6] MIPS: Loongson64: Move decode_cpucfg() to loongson_regs.h Tiezhu Yang
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