AM4372: System with 2x512MB RAM chips, but the system report only 512MB

albgarc2014

Part Number: AM4372

Hi TI,

I have a design based on an AM4372x with 2 RAM memories of 512MB each. The output of the system there are 512 MB, please see the picture.

I don't know if the system should say 1GB, or is it normal that it shows 512MB.

Is this normal or the system recognizes only one RAM and in that case I have a configuration problem?

Attention: Both memories share the same address bus (A0-A14) and each memory has 16bits on the data bus (D0-15 -> RAM1, D16-31 -> RAM2). This is why I think that maybe this system output is normal.

Thank you very much. Best Regards.

over 4 years ago

+1 Hong Guan64 over 4 years ago

TI__Guru 68960 points

Hi Alberto,
DDR size is "dynamically" determined in SPL/u-boot via calling get_ram_size() as listed below:

where dram_init() in "/arch/arm/mach-omap2/am33xx/board.c", and get_ram_size() in "/common/memsize.c"
/*
 * Check memory range for valid RAM. A simple memory test determines
 * the actually available RAM size between addresses `base' and
 * `base + maxsize'.
 */
long get_ram_size(long *base, long maxsize){}

int dram_init(void)
{
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
	sdram_init();
#endif

	/* dram_init must store complete ramsize in gd->ram_size */
	gd->ram_size = get_ram_size(
			(void *)CONFIG_SYS_SDRAM_BASE,
			CONFIG_MAX_RAM_BANK_SIZE);
	return 0;
}
where for AM437x EVM (2GB DDR)
- /include/configs/am43xx_evm.h
#define CONFIG_MAX_RAM_BANK_SIZE	(1024 << 21)	/* 2GB */
- /include/configs/ti_armv7_common.h
#define CONFIG_SYS_SDRAM_BASE		0x80000000

On DDR connection options, have you cross-referenced section 5.12.8.2 Memory Interface in AM43xx datasheet (www.ti.com/.../am4379)

Best,
-Hong

0 albgarc2014 over 4 years ago in reply to Hong Guan64

Genius 3520 points

Hi Hong Guan64,

Thank you very much,

My question is if in a hardware like the one I show in the attached image, is it normal for the system to detect 512MB, or should it detect 1GB?

Thank yuo very much.

+1 Hong Guan64 over 4 years ago in reply to albgarc2014

TI__Guru 68960 points

Hi Alberto,
Following up my last reply, let me use Linux SDK 6.3 as an example:
By default, for AM437x EVM (2GB DDR)

- /include/configs/am43xx_evm.h
#define CONFIG_MAX_RAM_BANK_SIZE	(1024 << 21)	/* 2GB */

The u-boot log would be:
U-Boot 2019.01-g175b3522cc-dirty (Apr 26 2021 - 15:31:10 -0500)
...
DRAM:  2 GiB
...

If I make one change as listed below in u-boot code:

- /include/configs/am43xx_evm.h
#define CONFIG_MAX_RAM_BANK_SIZE	(1024 << 20)	/* 1GB */

I'm attaching the new log file with the above u-boot change, where
...
DRAM: 1 GiB
...

Can we check "CONFIG_MAX_RAM_BANK_SIZE" configuration in your u-boot?
- /include/configs/am43xx_evm.h
#define CONFIG_MAX_RAM_BANK_SIZE ???

Best,
-Hong

Fullscreen am4_6.3_ddr_size_testing.txt Download

U-Boot SPL 2019.01-g175b3522cc-dirty (Apr 26 2021 - 15:31:10 -0500)
Trying to boot from MMC1
...
U-Boot 2019.01-g175b3522cc-dirty (Apr 26 2021 - 15:31:10 -0500)
...
DRAM:  1 GiB
...
Hit any key to stop autoboot:  2  1  0 
=> bdinfo
arch_number = 0x00000000
boot_params = 0x80000100
DRAM bank   = 0x00000000
-> start    = 0x80000000
-> size     = 0x40000000
baudrate    = 115200 bps
TLB addr    = 0xbfff0000
relocaddr   = 0xbff4c000
reloc off   = 0x3f74c000
irq_sp      = 0xbdf2ca60
sp start    = 0xbdf2ca50
Early malloc usage: b50 / 2000
fdt_blob    = 0xbdf2ca78
=>

0 albgarc2014 over 4 years ago in reply to Hong Guan64

Genius 3520 points

Ok, I understand. Thank you very much!

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AM4372: System with 2x512MB RAM chips, but the system report only 512MB