[U-Boot] [issue report] mainline u-boot was stuck before booting kernel

Sandy Patterson
2016-07-26T13:16:20Z

Hi Ziyuan, good work!

This does in fact fix it for me.

I followed through your notes. What is isr() supposed to do? it looks like
it just tells the compiler that the memory cache has been invalidated. But
in the TRM it says we need to actually do an ISB.

Would fixing the dcache flush so it does an ISB when it disables the MMU
maybe be an alternative solution? (I couldn't figure out which macro I
should be using. isb() is defined for arm64 to do the actual op.

Anyway, the following also fixes for me.

diff --git a/arch/arm/lib/cache-cp15.c b/arch/arm/lib/cache-cp15.c
index 1121dc3..3494a5c 100644
--- a/arch/arm/lib/cache-cp15.c
+++ b/arch/arm/lib/cache-cp15.c
@@ -217,6 +217,8 @@ static void cache_disable(uint32_t cache_bit)
if (cache_bit == (CR_C | CR_M))
flush_dcache_all();
set_cr(reg & ~cache_bit);
+ if(cache_bit & CR_M)
+ asm volatile ("isb" : : : "memory");
}
#endif

I'm not sure what kinds of side effects for other boards these changes
would have.

On Tue, Jul 26, 2016 at 8:15 AM, Ziyuan Xu <xzy.xu@rock-chips.com> wrote:

> + Simon and heiko
>
> On 2016?07?26? 14:30, Ziyuan Xu wrote:
>
>> Dear All,
>>
>> I add the ISB operation after dcache_disable(), and I can jump to linux
>> kernel entry.:-)
>>
>> diff --git a/arch/arm/cpu/armv7/cpu.c b/arch/arm/cpu/armv7/cpu.c
>> index 6eac5ef..5cc09ba 100644
>> --- a/arch/arm/cpu/armv7/cpu.c
>> +++ b/arch/arm/cpu/armv7/cpu.c
>> @@ -43,6 +43,7 @@ int cleanup_before_linux_select(int flags)
>> */
>> dcache_disable();
>> v7_outer_cache_disable();
>> + ISB;
>>
>> /*
>> * After D-cache is flushed and before it is disabled
>> there may
>>
>> Sounds crazy. In fact, there is already an 'ISB' operation in set_cr()
>> which to disable dcache and MMU. But it just tell processor that memory
>> had change, not real ISB for armv7.
>>
>> dcache_disable
>> ==>flush_dcache_all()
>> ==>set_cr() disable dcache and MMU.
>>
>> #define isb() __asm__ __volatile__ ("" : : : "memory")
>> static inline void set_cr(unsigned int val)
>> {
>> if (is_hyp())
>> asm volatile("mcr p15, 4, %0, c1, c0, 0 @ set CR" :
>> : "r" (val)
>> : "cc");
>> else
>> asm volatile("mcr p15, 0, %0, c1, c0, 0 @ set CR" :
>> : "r" (val)
>> : "cc");
>> isb();
>> }
>>
>> I also find something in ARM cortex-A17 TRM. ==>"Disable the MMU from the
>> each processor followed by an ISB to ensure the MMU disable operation is
>> complete, then followed by a DSB to drain previous memory transactions."
>>
>> In my humble opinion, maybe instructions tlb had alter, and cause running
>> away??? I'm not sure about it.
>> @Sandy, could you have a try with my update?
>>
>> @Simon, did you hit this glitch? I hope you can help ...:-)
>>
>> On 2016?07?25? 23:00, Sandy Patterson wrote:
>>
>>> Ah, thanks. Your debugging looks the same as what I've seen from printf
>>> debugging. I'll try to verify though.
>>>
>>> On Mon, Jul 25, 2016 at 10:58 AM, Ziyuan Xu <xzy.xu@rock-chips.com
>>> <mailto:xzy.xu@rock-chips.com>> wrote:
>>>
>>> hi Stany,
>>>
>>> The difference is that you print out assertion log.
>>>
>>> Reset not supported on this platform
>>> ### ERROR ### Please RESET the board ###
>>>
>>> You can add show_boot_progress() function in your bsp file to find
>>> out something.
>>> #define CONFIG_SHOW_BOOT_PROGRESS
>>> void show_boot_progress(int progress)
>>> {
>>> printf("Boot reached stage %d\n", progress);
>>>
>>> }
>>>
>>>
>>> On 2016?07?25? 22:12, Ziyuan Xu wrote:
>>>
>>> Hi All,
>>>
>>> I'm sorry to tell you that I failed to boot linux kernel with
>>> the mainline u-boot on rk3288 board(both evb-rk3288 &
>>> fennec-rk3288). It was stuck in cleanup_before_linux() before
>>> jumping to linux, and the boot_stage_flag is
>>> BOOTSTAGE_ID_BOOTM_HANDOFF.
>>>
>>> ## Current stack ends at 0x7df638b0 * kernel: cmdline image
>>> address = 0x02000000
>>> ## No init Ramdisk
>>> ramdisk start = 0x00000000, ramdisk end = 0x00000000
>>> ## No Flattened Device Tree
>>> Continuing to boot without FDT
>>> Initial value for argc=3
>>> Final value for argc=3
>>> using: ATAGS
>>> ## Transferring control to Linux (at address 02000000)...
>>>
>>> Starting kernel ...
>>>
>>> With the further investigation, it never returnned back from
>>> invalidate_dcache_all(). I mean that I can't reach stage 4 as
>>> below.
>>>
>>> cleanup_before_linux
>>> ==>cleanup_before_linux_select
>>> ==>1.disable_interrupts
>>> ==>2.dcache_disable
>>> ==>3.invalidate_dcache_all
>>> ==>4.icache_disable
>>>
>>> Debug further, invalidate_dcache_all invalidate all cache
>>> one-by-one which cache type is DATA_ONLY, INSTRUCTION_DATA or
>>> UNIFIED. And invalidate way from one set to another set in
>>> order. The problem is that the PC ran away in invalidate way
>>> loop [cache level L1!!!].
>>>
>>> I add some serial output code in __v7_flush_dcache_all to
>>> figure out the bog.
>>> I expect:
>>> Print the value of r9 in sequence, e.g 0x7f, 0x7e, 0x7d.....
>>> 0x01, 0x00 (hex)
>>> In fact, print the value of r9 in sequence at first, but print
>>> unexpected value afterwards. e.g 0x7f, 0x7e, 0x7d, ..,0x73,
>>> 0x40, 0x85,....
>>>
>>> ENTRY(__v7_flush_dcache_all)
>>> [snip]
>>> loop1:
>>> mov r9, r7 @ create working copy of max
>>> index
>>> loop2:
>>> + stmfd sp!, {r0}
>>> + ldr r0, =0xff690000
>>> + str r9, [r0]
>>> + ldmfd sp!, {r0}
>>> ARM( orr r11, r10, r4, lsl r5 ) @ factor way and
>>> cache number into r11
>>> THUMB( lsl r6, r4, r5 )
>>> THUMB( orr r11, r10, r6 ) @ factor way and
>>> cache number into r11
>>> ARM( orr r11, r11, r9, lsl r2 ) @ factor index
>>> number into r11
>>> THUMB( lsl r6, r9, r2 )
>>> THUMB( orr r11, r11, r6 ) @ factor index
>>> number into r11
>>> mcr p15, 0, r11, c7, c14, 2 @ clean & invalidate
>>> by set/way
>>> subs r9, r9, #1 @ decrement the index
>>> bge loop2
>>> subs r4, r4, #1 @ decrement the way
>>> bge loop1
>>> skip:
>>> ENDPROC(__v7_flush_dcache_all)
>>>
>>> I don't have the jtag, hence I can't address the current pc. I
>>> have no doubt that if any glitches in __v7_flush_dcache_all, I
>>> reviewed several times, also copy kernel's implement to here.
>>> :-( No effect.
>>> A more interesting thing is that Sandy had report it. He and I
>>> have similar problem. Everything work fine after I applied his
>>> patches, or disable dcache(active CONFIG_SYS_DCACHE_OFF).
>>> @Stany, I'm sorry that I disable dcache during hack.. That was
>>> a mistake:-(
>>>
>>> @Simon & hieko,
>>> Can you boot linux with the mainline u-boot? have a try?
>>>
>>>
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>>>
>>>
>>>
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>>>
>>
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