Linux/AM4376: ROM Loader or U-Boot changes CTRL_STS register

Bernhard Blattmann21

Part Number: AM4376

Tool/software: Linux

Hi,

Something in the ROM Loader or U-Boot changes the CTRL_STS register and therefore the SYSBOOT register. This leads to a wrong setting of the system clock and a wrong restart behavior after a warm reset.

Can you give me any hints where the CTRL_STS register are manipulated in the original ROM loader or U-Boot? We could not find anything in the U-Boot code.

Overwriting the register in the u-boot solves the issue, but i really did not expect that something would overwrite the SYSBOOT information and I'm wondering if other registers are also altered unexpectedly.

thanks for your feedback

Bernhard

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

Please post:

1. Linux/U-boot version you use.
2. Hardware SYSBOOT settings
3. Expected and wrong contents of CTRL_STS

0 Bernhard Blattmann21 over 7 years ago in reply to Biser Gatchev-XID

Prodigy 50 points

ti-u-boot-2017.01
Linux version 4.9.41

set on HW-SYBOOT Pins:
000 10000000 00101000

CTRL_STS read at the beginning of get_sys_clk_index() (arch/arm/mach-omap2/am33xx/sys_info.c):
0x00000301

CTRL_STS set in get_sys_clk_index() (arch/arm/mach-omap2/am33xx/sys_info.c) to correct clock setting and boot sequence:
0x00800308

0 Rex Chang over 7 years ago in reply to Bernhard Blattmann21

TI__Guru 50170 points

This is a duplcate thread of e2e.ti.com/.../749511
Please refer to the reply of the thread.

For different boot mode, the u-boot needs to be built differently using different config file.

Rex

0 Bernhard Blattmann21 over 7 years ago in reply to Rex Chang

Prodigy 50 points

the problem is not booting from qspi, i marked the thread e2e.ti.com/.../749511 as solved, and could not unmark it properly, that's why i started a new thread with the further findings here (we successfully generated different u-boot images and can boot from qspi and sd-card)

the problem is that the CTRL_STS register is altered at some point in the boot process, before u-boot is finished starting up. This alters the clock settings and the boot sequence, therefore a warm reset fails because the bootsequence is not as configured with the SYS_BOOT pins.

0 Rex Chang over 7 years ago in reply to Bernhard Blattmann21

TI__Guru 50170 points

Hi, Bernhard,

Have you tried to build MLO using different defconfig as described in U-boot User's Guide? On TI's EVM, there isn't DIP Switch to configure boot mode. For different boot mode, it uses different MLO/u-boot images.

Rex

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Linux/AM4376: ROM Loader or U-Boot changes CTRL_STS register