DDR3 512M

CKamas

Hi all,

I am trying to activate the second half of my DDR3 memory. It works just fine if I use the default memory size of 256M. I can run the memsize command and it stops at 256M as expected.

If I modify the uBoot boot args to have mem=512M and rerun the memsize command the kernel oopses.

Where should I look for the issue?

Chuck

root@am335x-evm:~# mem
memInfo.sh mem_util    memsize
root@am335x-evm:~# memsize
[   30.772792] ------------[ cut here ]------------
[   30.777717] kernel BUG at mm/slab.c:501!
[   30.781867] Internal error: Oops - undefined instruction: 0 [#1] PREEMPT

over 10 years ago

0 CKamas over 10 years ago

Intellectual 780 points

0 CKamas over 10 years ago in reply to CKamas

Intellectual 780 points

0 Biser Gatchev-XID over 10 years ago in reply to CKamas

TI__Guru**** 393215 points

The schematics seems OK. Have you followed the DDR3 configuration guidelines? Links are as follows:

http://processors.wiki.ti.com/index.php/AM335x_EMIF_Configuration_tips

http://processors.wiki.ti.com/index.php/AM335x_DDR_PHY_register_configuration_for_DDR3

Especially check the SDRAM_CONFIG register.

0 CKamas over 10 years ago in reply to Biser Gatchev-XID

Intellectual 780 points

Biser,

Thanks.

Where can I find the configuration of the SDRAM_CONFIG register in Linux?

Chuck

0 Biser Gatchev-XID over 10 years ago in reply to CKamas

TI__Guru**** 393215 points

It should be in ddr_defs.h header file found in arch/arm/include/asm/arch-am33xx/. Check this link: http://processors.wiki.ti.com/index.php/Sitara_Linux_Training:_Tuning_the_DDR3_Timings_on_BeagleBoneBlack#Updating_SPL.2FU-boot

0 CKamas over 10 years ago in reply to Biser Gatchev-XID

Intellectual 780 points

Biser,

Thank you for your help. I was able to follow the tutorials you recommended and get the optimal timing.

I found out the root cause of the top 256Mb of the Dram not working... we failed to hook up A15. We will fix it in the next spin, and come back to this issue.

Thanks!

Chuck

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DDR3 512M