When system reboot PMIC will reset and SW2 will off

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When system reboot PMIC will reset and SW2 will off

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wangvictor
Contributor III

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!

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3 Replies

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igorpadykov
NXP TechSupport
NXP TechSupport

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
Contributor III

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?

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133 Views
igorpadykov
NXP TechSupport
NXP TechSupport

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

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