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

Ziyuan Xu
2016-07-26T06:30:13Z

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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