Messages in this thread | | | Date | Tue, 31 Aug 2010 15:02:07 +0800 | Subject | Re: [PATCH 1/1] ARM: pxa168: fix corrected reset vector | From | Haojian Zhuang <> |
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On Tue, Aug 31, 2010 at 2:48 PM, Mark F. Brown <mark.brown314@gmail.com> wrote: > On Tue, Aug 31, 2010 at 2:26 AM, Haojian Zhuang > <haojian.zhuang@gmail.com> wrote: >> On Tue, Aug 31, 2010 at 2:08 PM, Eric Miao <eric.y.miao@gmail.com> wrote: >>> On Tue, Aug 31, 2010 at 2:04 PM, Eric Miao <eric.y.miao@gmail.com> wrote: >>>> On Tue, Aug 31, 2010 at 2:02 PM, Mark F. Brown <mark.brown314@gmail.com> wrote: >>>>> On Tue, Aug 31, 2010 at 1:48 AM, Eric Miao <eric.y.miao@gmail.com> wrote: >>>>>> On Thu, Aug 26, 2010 at 5:07 PM, Mark F. Brown <mark.brown314@gmail.com> wrote: >>>>>>> Signed-off-by: Mark F. Brown <mark.brown314@gmail.com> >>>>>>> --- >>>>>>> arch/arm/mach-mmp/include/mach/system.h | 2 +- >>>>>>> 1 files changed, 1 insertions(+), 1 deletions(-) >>>>>>> >>>>>>> diff --git a/arch/arm/mach-mmp/include/mach/system.h b/arch/arm/mach-mmp/include/mach/system.h >>>>>>> index 4f5b0e0..926e9c0 100644 >>>>>>> --- a/arch/arm/mach-mmp/include/mach/system.h >>>>>>> +++ b/arch/arm/mach-mmp/include/mach/system.h >>>>>>> @@ -16,6 +16,6 @@ static inline void arch_idle(void) >>>>>>> >>>>>>> static inline void arch_reset(char mode, const char *cmd) >>>>>>> { >>>>>>> - cpu_reset(0); >>>>>>> + cpu_reset(0xffff0000); >>>>>> >>>>>> Not sure if this correct. But normally reset jump happens after we turn >>>>>> off the MMU and so on. Ain't the BootROM starts from 0 ? >>>>>> >>>>>>> } >>>>>>> #endif /* __ASM_MACH_SYSTEM_H */ >>>>>>> -- >>>>>>> 1.7.0.4 >>>>>>> >>>>>>> >>>>>> >>>>> >>>>> Eric, the boot-rom for pxa168 starts at 0xffff_0000. I am pretty sure >>>>> about that! If you set the reset vector to 0x0 it will crash during >>>>> reboot. I will send you xdb snapshots if you need me to. >>>>> >>>> >>>> OK, you are expert on this :-) >>>> >>>> Applied to 'fix'. >>>> >>> >>> One moment. Since this is really global to pxa910 and mmp2, so I >>> suggest this being fixed for pxa168 only first. How about this: >>> >>> ARM: pxa168: fix corrected reset vector >>> >>> Reset vector for pxa168 is 0xffff_0000 not 0x0. This fix allows >>> reboot to work >>> >>> Signed-off-by: Mark F. Brown <mark.brown314@gmail.com> >>> >>> diff --git a/arch/arm/mach-mmp/include/mach/system.h >>> b/arch/arm/mach-mmp/include/mach/system.h >>> index 4f5b0e0..1a8a25e 100644 >>> --- a/arch/arm/mach-mmp/include/mach/system.h >>> +++ b/arch/arm/mach-mmp/include/mach/system.h >>> @@ -9,6 +9,8 @@ >>> #ifndef __ASM_MACH_SYSTEM_H >>> #define __ASM_MACH_SYSTEM_H >>> >>> +#include <mach/cputype.h> >>> + >>> static inline void arch_idle(void) >>> { >>> cpu_do_idle(); >>> @@ -16,6 +18,9 @@ static inline void arch_idle(void) >>> >>> static inline void arch_reset(char mode, const char *cmd) >>> { >>> - cpu_reset(0); >>> + if (cpu_is_pxa168()) >>> + cpu_reset(0xffff0000); >>> + else >>> + cpu_reset(0); >>> } >>> #endif /* __ASM_MACH_SYSTEM_H */ >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> Please read the FAQ at http://www.tux.org/lkml/ >>> >> The reset code is in below. >> >> .align 5 >> ENTRY(cpu_mohawk_reset) >> mov ip, #0 >> mcr p15, 0, ip, c7, c7, 0 @ invalidate I,D caches >> mcr p15, 0, ip, c7, c10, 4 @ drain WB >> mcr p15, 0, ip, c8, c7, 0 @ invalidate I & D TLBs >> mrc p15, 0, ip, c1, c0, 0 @ ctrl register >> bic ip, ip, #0x0007 @ .............cam >> bic ip, ip, #0x1100 @ ...i...s........ >> mcr p15, 0, ip, c1, c0, 0 @ ctrl register >> mov pc, r0 >> >> MMU is disabled at here and replace PC with r0 value. I doubt code >> executed correctly at here. While MMU is disabled, the PC should be >> continue in the range of 0xCxxx_xxxx (kernel space). "mov pc, r0" >> shouldn't be executed. Instruction fetch failure should occurs since >> there's no physical address in 0xCxxx_xxxx. >> >> Correct me if I'm wrong. >> >> Thanks >> Haojian >> > > Haojian, > > I think there is a pipeline execution of the mov pc, r0 instruction. > If I remember correctly you need to do a similar jump when you turn > the MMU on in early boot code. If it makes any difference I did test > this code on pxa168 before submitting it. I will double check the mmp2 > and the pxa910 reset vectors with the Boot ROM developers. >
In early boot code, 1:1 (physical:virtual) mapping is used. It means that physical address is same as virtual address. So you can operature mmu as you wish.
By the way, I don't suggest to reset CPU by this way. Reset is not only make code running from the head, it should also clear registers and RTL logic in CPU. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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