On Mon, Mar 29, 2010 at 5:09 PM, Becky Bruce beckyb@kernel.crashing.org wrote:
--- a/board/freescale/mpc8641hpcn/mpc8641hpcn.c +++ b/board/freescale/mpc8641hpcn/mpc8641hpcn.c @@ -72,6 +72,8 @@ initdram(int board_type) dram_size = fixed_sdram(); #endif
- adjust_ddr_bat(dram_size);
By doing this here, you still have a (small) window where the problem could occur.
U-Boot hasn't relocated yet, so it's not using any of the DDR. I don't see how there could be a problem.
It's highly unlikely, but we might still have problems going forward. I think we might need to:
- remove the write of BAT0 from setup_bats (add a comment). This
way, there is no BAT setup for the DDR until right after we configure the controller
Ok, I get it now. It will catch anyone trying to write to DDR before it's really set up. I can do that.
- change the name "adjust_ddr_bat" to "setup_ddr_bat" or something
similar. I haven't dug around too much to see if this causes problems, but I am able to boot my 8641 this way.
Ok.
- Change setup_ddr_bat so that it just does a write (remove the BL
from the #defined values for the default BAT0 and or them in here instead, and add a comment to the config file that says BL is determined dynamically
Ok.
I think you need to adjust how much usable ram u-boot thinks it has if you can't map it all.
I tried that. The problem is that U-Boot uses this number to tell Linux how much DDR there is. The code doesn't really support U-Boot and Linux seeing different amounts of DDR.
If you have one BAT, and you have an amount of memory that is ! a power of 2, then you're going to leave a chunk unmapped, which can cause problems later.
AFAIK, we always have only one BAT for DDR. I wasn't planning on expanding the scope of this patch to add support for multiple BATs.
I don't know how to handle !2^X sizes of DDR.
+#define KB_TO_BATU(x) ((((x)/128) - 1) * 4) /* Convert KBs to BATU value */
It seems somewhat arbitrary that you decided to use take KB here as an arg when the BATU_SIZE macro returns bytes. I'd prefer to see symmetry here.
I used KB to keep the sizes of numbers small. The smallest value is 128KB, so it's not *that* arbitrary.