When system reboot PMIC will reset and SW2 will off

[wangvictor]

Hi Community,

I'm working on i.MX6 sabreSD DL with ubuntu 16.04.

I built image via Yocto Project.

Here is an issues that I'm dealing with.

1. When I reboot the system, PMIC's SW2 which my hardware designed it to be EMMC power was set to low then to high.
   And I assumed that is the reason why machine cannot restart after ran "reboot" command.
   
   

I tried to trace code and I found that when user ran reboot command, driver will execute kernel_restart.

Inside kernel_restart it execute syscore_shutdown.

What syscore_shutdown do is as below.

void syscore_shutdown(void)
{
struct syscore_ops *ops;

mutex_lock(&syscore_ops_lock);

list_for_each_entry_reverse(ops, &syscore_ops_list, node)
pr_err("PM: winmate victor PMIC not shutdown\n");
/*if (ops->shutdown) {
if (initcall_debug)
pr_info("PM: Calling %pF\n", ops->shutdown);
ops->shutdown();
}*//*winmate victor try*/

mutex_unlock(&syscore_ops_lock);
}

I tried to mark out below part to avoid PMIC shutdown.

if (ops->shutdown) {
if (initcall_debug)
pr_info("PM: Calling %pF\n", ops->shutdown);
ops->shutdown();
}

However SW2 still switched off.

Question:

1. Why did SW2 be switched off when execute reboot command?
2. How can I avoid the SW2 be switched off and on ?
3. Would SW2 switch off when PMIC reboot then switch on again?
4. If yes how can I avoid it? Or cannot?

Thanks in Advanced!

[igorpadykov]

Hi victor

for emmc issue one can try to assert emmc reset signal.

In general removing all power supplies is considered as correct reboot solution,

on Sabre SD spf-27392 schmetaic p.21 this is implemented by pmic PWRON-WDOG_B

toggling.

Schematics (1)
"Design files, including hardware schematics, Gerbers, and OrCAD files.

SABRE Platform for Smart Devices|NXP 

Best regards
igor
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[wangvictor]

Hardware design is all the same as freescale.

The Emmc that I used is Forseen.

Here I find a new clue.

After I reboot the system, cpu will get into download mode.

It seems that cpu cannot read anything from Emmc.

But If I try to use Kinston's Emmc, It will not appear the issue.

Is there any work around that can solve this problem for Forseen's Emmc?

[igorpadykov]

this issue may be specific for that particular emmc, you can ask vendor

of this emmc if there is specific power up sequence required.

Best regards
igor