Debugging x-loader for OMAP35xx

Andrew Jones91825

Hey folks,

A real newbie question and possibly a very stupid one.

My x-loader is not working the way it should from NAND flash and I'm trying to debug it. I'm using a custom board.

I've attached an LED to my board and I'm trying to blink it at various stages inside the x-loader source. I made a function called blinkTwice() (which blinks the LED twice), and that function contains some instances of delay(1000);.

However, when I launch my x-loader from MMC, just to test the LED flashing, x-loader appears to ignore all my calls to delay(1000) and blasts straight into u-boot and beyond.

For example:

                printf("before delay... \n");
                delay(1000);
                printf("after delay... \n");

Happens in the blink of an eye.

Thankyou all!

over 13 years ago

0 Andrew Jones91825 over 13 years ago

Intellectual 260 points

Okay, I found the solution.

It turns out that delay() was just very, very fast.

It executes a few assembly instructions each iteration, so it is even hard to catch with delay(1000);

/*******************************************************
* Routine: delay
* Description: spinning delay to use before udelay works
******************************************************/
static inline void delay(unsigned long loops)
{
__asm__ volatile ("1:\n" "subs %0, %1, #1\n"
"bne 1b":"=r" (loops):"0"(loops));
}

By defining a new function, you can increase the delay up to a duration useful for debugging x-loader:

static inline void pDelay(unsigned long us)
{
delay(us * 200 * 1000); /* approximate */
}

pDelay(1000) lasts for about 1 second.

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Debugging x-loader for OMAP35xx