Re: [U-Boot] [PATCH] MIPS: Add CONFIG_SKIP_LOWLEVEL_INIT and flush dcache upon relocation

On Sunday 16 November 2008, Shinya Kuribayashi wrote:

...

diff --git a/cpu/mips/start.S b/cpu/mips/start.S index 6a22302..5b71b00 100644 --- a/cpu/mips/start.S +++ b/cpu/mips/start.S @@ -243,9 +243,11 @@ reset: mtc0 zero, CP0_COUNT mtc0 zero, CP0_COMPARE

+#if !defined(CONFIG_SKIP_LOWLEVEL_INIT) /* CONFIG0 register */ li t0, CONF_CM_UNCACHED mtc0 t0, CP0_CONFIG +#endif /* !CONFIG_SKIP_LOWLEVEL_INIT */

/* Initialize $gp. */

It might be preferable to remove the /* CONFIG_SKIP_LOWLEVEL_INIT */ comment for better readability, IMHO.

Hmmm. I usually prefer to add those comments to the #else and #endif since it makes the code better readable. Especially when the chunks of code in-between gets bigger. So I would prefer to keep this comment. OK?

...

@@ -323,6 +327,14 @@ relocate_code: * t1 = target address * t2 = source end address */

• /*

• * Save destination address and size for later usage in flush_cache()
  

• */
  

• move t7, a1 /* save gd in t7 */
• move a0, t1 /* a0 <-- destination addr */
• sub a1, t2, t0 /* a1 <-- size */
• /* On the purple board we copy the code earlier in a special way
  • in order to solve flash problems
  */

@@ -338,6 +350,11 @@ relocate_code: /* If caches were enabled, we would have to flush them here. */

• /* a0 & a1 are already set up for flush_cache(start, size) */
• la t9, flush_cache
• jalr t9
• nop
• /* Jump to where we've relocated ourselves. */ addi t0, a2, in_ram - _start

@@ -387,7 +404,7 @@ in_ram: bltl t1, t2, 1b sw zero, 0(t1) /* delay slot */

• move a0, a1

• move a0, t7 /* a0 <-- gd */ la t9, board_init_r jr t9 move a1, a2 /* delay slot */

• Could we separate this flush_cache patch from this patch?

OK, will do.

• Please use save register, s[0-7], instead of t7, since t7 register might be overwritten with another value in flush_cache(). Furthermore, in this case, a2 should be saved as well.

I'm still new to MIPS so thanks for your suggestions. I'll try to provide a fixed up patch today.

Thanks.

Best regards, Stefan

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