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Re: Redboot hanging during boot on EP9302

Hi Andrew,

You misaddressed this to ecos-devel-owner instead of ecos-devel. I've CC'd it to ecos-devel for you in case anyone can help.

For what it's worth, in the 9 times out of 10 it works, is it solid? Might it be worth trying out the eCos "heaptest" test (perhaps increasing the iterations) to verify the stability of SDRAM in case the timings are marginal?


Andrew McKay wrote:
Hey guys,

I'm having issues with our EP93xx hanging during reboots with an external watchdog. It crashes 1 out of every 10 reboots or so. I the code is crashing in two places (that I've found so far). The first is when the code attempts to jump to code in RAM copied out of flash. The second is when the Intel Strata flash driver copies it's routine to RAM and tries to jump to it. The second case is a bit silly because the code is already executing from RAM. I think that it makes the assumption that it is executing in Flash, that's why the driver makes another copy of a routine in RAM.

The EP93xx code I'm using is from Cirrus Logic's 1.3.0 patches that they supplied with the processor. I also have their 1.4.5 patches, though we're not using that code for our current bootloader. On a quick look it didn't appear that there was any major differences in SDRAM setup and configuration.

Anyways the ep93xx's platform set up code the following happens:

        ldr     r0,=__rom_vectors_lma   // Relocate FLASH/ROM to RAM
        ldr     r1,=__rom_vectors_vma   // ram base & length
        ldr     r2,=__ram_data_end
20:     ldr     r3,[r0],#4
        str     r3,[r1],#4
        cmp     r1,r2
        bne     20b

        //Jump to ram
        ldr     r0,=30f
        mov     pc,r0
        // Turn on Green LED, Turn off the Red LED.
        ldr     r1, =EP9312_LED_DATA
        ldr     r0, [r1]
        eor     r0, r0, #(EP9312_LED_GREEN_ON | EP9312_LED_RED_ON)
        strb    r0,[r1]


In cases where it fails it never gets to the code in RAM.

I added a check in between the copy and the jump.

//lets do a compare of copied data!
        ldr     r0,=__rom_vectors_lma
        ldr     r1,=__rom_vectors_vma
        ldr     r2,=__ram_data_end
25:     ldr     r3,[r0],#4
        ldr     r4,[r1],#4
        cmp     r3,r4
        beq     26f
        //If we get here our copy was corrupted!  Turn on LEDs to warn!!!
        ldr     r3,=0x80840040
        ldr     r4,=0x0
        str     r4,[r3]
26:     cmp     r1,r2
        bne     25b

When the board crashes booting up, the LEDs I turn on in this code are on signaling that the copy failed.

I suspect there is possibly an issue initializing the SDRAM on a warm boot. I don't suspect it's an issue with NOR flash for two reasons. First, I have checked the setup for NOR Flash and it is running with the most conservative timings possible. Secondly, code is executing out of NOR flash prior to the jump to RAM.

I'm currently going through the SDRAM initialization code to see if I can find a problem, but so far I haven't. Though I'm not through all of it with a fine tooth comb yet.

I can work around the problem by using an external watchdog to reboot the system if the jump isn't successful. However I don't like that as a permanent solution because it's coving up an underlying issue with SDRAM as far as I can tell.

Does anyone have any ideas, solutions, or recommendations? Any help at all would be greatly appreciated.

Andrew McKay
Iders Inc.

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