AM5728: Issues with WDT enabled in U-boot

Hi Paul,

Paul Burkacki said:

When the extra call to hw_watchdog_init() (added by me) is not present in board_init(), regardless of whether a I return a 1 or a 0 from board_init(), the first set of calls to hw_watchdog_*() functions always appears.  I am not sure where they are coming form.

The first invocation of hw_watchdog_init() happens in the context of SPL, and comes from here:

arch/arm/mach-omap2/boot-common.c:

void spl_board_init(void)
{
#ifdef CONFIG_SPL_SERIAL_SUPPORT
        /* Prepare console output */
        preloader_console_init();
#endif
#if defined(CONFIG_SPL_NAND_SUPPORT) || defined(CONFIG_SPL_ONENAND_SUPPORT)
        gpmc_init();
#endif
#if defined(CONFIG_SPL_I2C_SUPPORT) && !defined(CONFIG_DM_I2C)
        i2c_init(CONFIG_SYS_OMAP24_I2C_SPEED, CONFIG_SYS_OMAP24_I2C_SLAVE);
#endif
#if defined(CONFIG_AM33XX) && defined(CONFIG_SPL_MUSB_NEW_SUPPORT)
        arch_misc_init();
#endif
#if defined(CONFIG_HW_WATCHDOG)
        hw_watchdog_init();
#endif
#ifdef CONFIG_AM33XX
        am33xx_spl_board_init();
#endif
#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_REMOTEPROC_TI_IPU)
        spl_boot_ipu();
#endif
}

Paul Burkacki said:

I also don't understand why, even though the HW WDT timer is not enabled, a board hangs and never restarts again.

Can you please describe in more detail what you mean by "HW WDT timer not enabled".

Paul Burkacki said:

The reason I add an explicit call to hw_watchdog_init() in board_init() is because without it, the board hangs after boot and never restarts. 

You say the board boots and then hangs... how far does it boot?

Let me see if I can get a hold of an AM57xx EVM tomorrow and give this a try.

Regards, Andreas

Hi Andreas,

thank you for your reply and thank you for pointing out the location of the first call to hw_watchog_init().  That makes more sense now.

In regard to my comment of "HW WDT timer not enabled", I made a mistake when I wrote it.  Above, I wrote

Paul Burkacki: I also don't understand why, even though the HW WDT timer is not enabled, a board hangs and never restarts again.

What I meant to say was:

Paul Burkacki: I also don't understand why, even though the HW WDT timer _is_ enabled, a board hangs and never restarts again.

So the mixup in my question was caused by my lack of understanding why the first call to hw_watchdog_init(), the one made in spl_board_init() as you pointed out, does not force a reboot of the board when board_init() is forced to return a 1.  I thought that this first call enables the WDT such that, when the predefined 60 second mark is reached, the board should be rebooted.  In effect, that first call should not require that a second call is added to AM57xx specific board_init().  As I mentioned in my original post, it seems that the extra call to hw_watchdog_init(), which I add in AM57xx specific board_init(), is required in order for the 60 second timeout to cause a reboot.

In regard to my comment of "the board hangs after boot and never restarts".  The following is the console output I see when the call to hw_watchdog_init() is made only from spl_board_init() and I return a 1 from the AM57xx specific board_init() without making an explicit call to hw_watchdog_init().  In this case, the 60 second HW WDT timeout does not seem to force a board reboot.  Here is the console output which I observed:

U-Boot SPL 2018.01-g131dc82830 (Nov 04 2019 - 00:56:49)
DRA752-GP ES2.0
******** hw_watchdog_init() called! ************
************************************************
******** hw_watchdog_disable() called! *********
************************************************
******** omap_wdt_set_timeout() called! ********
************************************************
Trying to boot from MMC2_2
no pinctrl state for default mode
palmas_i2c_write_u8: chip=58 reg=51 val=43
palmas_i2c_write_u8: chip=58 reg=50 val=5
no pinctrl state for default mode
*** Warning - bad CRC, using default environment

reading u-boot.img
reading u-boot.img
reading u-boot.img
reading u-boot.img

U-Boot 2018.01-g131dc82830 (Nov 04 2019 - 00:56:49 +0000)

CPU : DRA752-GP ES2.0
Model: TI AM5728 IDK
Board: Humatics ALB REV
DRAM: 2 GiB
******** board_init(), not calling hw_watchdog_init() ********
**************************************************************
initcall sequence fefb1734 failed at call 80803c1d (err=1)
### ERROR ### Please RESET the board ###

Now I understand where the first set of calls to hw_watchdog_*() functions comes from.  But if I understand them correctly, they should be enough to enable HW WDT such that a reboot takes place at the 60 second mark.  Instead, the board hangs here for ever.

One more thing I should mention, the hw_watchdog_reset() function is called repeatedly in very fast succession during boot.  This would explain why the board reboot does not occur.  However, I don't understand why this function is called so rapidly.

Thank you again for your help.

Regards,

Paul

Part Number: AM5728

Hi Andreas,

when I clicked the "This answer resolved my question" button, the thread was locked.  I wasn't sure if you would be able to reply to it.  That is the only reason I am once more posting that last question here about the test method you used to confirm that your WDT changes worked.  I apologize if this turns out to be spam.  I was just making sure that it was still possible for you to reply to that one question.

Again, your previous post did resolve my question.  The one about the test method was the only one left.  Thanks again.

Regards,

Paul