| Message ID | 1603958581-4723-2-git-send-email-yangtiezhu@loongson.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Modify some registers operations and move decode_cpucfg() to loongson_regs.h | expand |
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? Thanks. - Jiaxun
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. And also we can see the following description in the chapter "9.45 Configuration Register 3 (CP0 Register 16, Select 3)" of MD00091-2B-MIPS64PRA-AFP-05.04: "The Config3 register encodes additional capabilities. All fields in the Config3 register are read-only." Thanks, Tiezhu > > Thanks. > > - Jiaxun
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? Thanks - Jiaxun
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
diff --git a/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h b/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h index 87a5bfb..e4d77f4 100644 --- a/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h +++ b/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h @@ -19,10 +19,6 @@ .macro kernel_entry_setup .set push .set mips64 - /* Set LPA on LOONGSON3 config3 */ - mfc0 t0, CP0_CONFIG3 - or t0, (0x1 << 7) - mtc0 t0, CP0_CONFIG3 /* Set ELPA on LOONGSON3 pagegrain */ mfc0 t0, CP0_PAGEGRAIN or t0, (0x1 << 29) @@ -54,10 +50,6 @@ .macro smp_slave_setup .set push .set mips64 - /* Set LPA on LOONGSON3 config3 */ - mfc0 t0, CP0_CONFIG3 - or t0, (0x1 << 7) - mtc0 t0, CP0_CONFIG3 /* Set ELPA on LOONGSON3 pagegrain */ mfc0 t0, CP0_PAGEGRAIN or t0, (0x1 << 29) diff --git a/arch/mips/loongson64/numa.c b/arch/mips/loongson64/numa.c index cf9459f..c7e3cced 100644 --- a/arch/mips/loongson64/numa.c +++ b/arch/mips/loongson64/numa.c @@ -40,9 +40,6 @@ static void enable_lpa(void) unsigned long value; value = __read_32bit_c0_register($16, 3); - value |= 0x00000080; - __write_32bit_c0_register($16, 3, value); - value = __read_32bit_c0_register($16, 3); pr_info("CP0_Config3: CP0 16.3 (0x%lx)\n", value); value = __read_32bit_c0_register($5, 1);
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(-)