i.MX6DL LPDDR2 suspend / resume issue with Linux kernel 4.1.15

[torstenkrieger]

We have an issue with iMX6DL and power-saving. On our custom-board we have implemented an LPDDR2 RAM (Micron EDB8164B4 ) to achieve better low-power. When we bring Linux in Suspend-to-RAM it goes to sleep but pushing an wake-up button results in an reboot instead of wake-up and back to normal operation. On sabresd-board (iMX6DL) the same Linux kernel works as expected.

I have found following thread with similar issue:

https://community.nxp.com/docs/DOC-94922

but unfortunately this patch applies to an older kernel version, we use Linux 4.1.15 from NXP git repository. For u-boot we use version 2016.11-rc3, however we have done all configuration and calibration for LPDDR2 in u-boot, RAM stress test has been also passed successfully.     

Here is the output of “uname –a”

Linux imx6dlsabresd 4.1.15-1.2.0+g77f6154 #1 SMP PREEMPT Mon Nov 28 11:05:20 CET 2016 armv7l GNU/Linux

Console snapshot when system is going to sleep and push button for wake-up.

======================================================

root@imx6dlsabresd:~# echo mem > /sys/power/state

PM: Syncing filesystems ... done.

Freezing user space processes ... (elapsed 0.005 seconds) done.

Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.

Suspending console(s) (use no_console_suspend to debug)

>>>>>>   BUTTON FOR WAKE-UP HAS BEEN PUSCHED    <<<<<<

U-Boot 2016.11-rc3-svn209 (Dec 14 2016 - 10:47:19 +0100)

======================================================

Many thanks in advanced for your support.

Regards,

Torsten

[bandarulavanya]

Hi Torsten Krieger,

I am facing same problem but my kernel version is 3.14.28. In "echo mem > /sys/power/state" after interrupt system is rebooting instead of restart If i use 3.0.35 kernel with that patches it works fine. But my requirement is i should use 3.14.28 kernel. How you solved this issue can you help me to solve this issue if you already solved.

Thanks & Regards,

Lavanya

[Yuri]

Hello,

   Please check schematic differences between Your board and the NXP
design. Also, please use Chapter 21 [Low-level Power Management (PM)
Driver] of “i.MX_Linux_Reference_Manual.pdf” for implementation details. 

Have a great day,

Yuri

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