am335x resume from suspend mode failed

Eric Cheng1

Hi Sirs,

I are working a custom board, but It can not resume from suspend mode, no matter resume by GPIO or RTC or Touchscreen.

Does anyone meet the problem? Is there any direction for fix the bug?

1.Touchscreen

~#echo enabled > /sys/devices/platform/omap/ti_tscadc/power/wakeup
~#echo mem > /sys/power/state
[ 396.078918] PM: Syncing filesystems ... done.
[ 396.086883] Freezing user space processes ... (elapsed 0.01 seconds) done.
[ 396.110809] Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
[ 396.288146] PM: suspend of devices complete after 156.585 msecs
[ 396.296112] PM: late suspend of devices complete after 1.678 msecs

After push the touch pad, we got below and system hang.

[ 409.372375] GFX domain entered low power state
[ 409.377105] Successfully transitioned all domains to low power state
[ 409.589813] PM: early resume of devices complete after 205.627 msecs

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi Eric,

What type of memory do you have on your board? Check the DDR_CKE signal. Does it go low in suspend? There must be an external 10kOhm pulldown on this signal. If it's DDR3 and you have Vtt termination, DDR_CKE must not be terminated.

0 Eric Cheng1 over 10 years ago in reply to Biser Gatchev-XID

Intellectual 320 points

Hi Giser,

Below are DDR3 specification for you reference.

Density	2Gb	RoHS	Yes
Depth	128Mb	Width	x16
Voltage	1.5V	Package	FBGA
Pin Count	96-ball	Clock Rate	800 MHz
Cycle Time	1.25ns	Op. Temp.	0C to +95C
CL	CL = 11	Data Rate	DDR3-1600
Features		Brand	Micron

0 Eric Cheng1 over 10 years ago in reply to Biser Gatchev-XID

Intellectual 320 points

Hi Biser,

Yes. The DDR_CKE signal already connect an external 10kOhm, as below:

Is there any other suggestion for me? The schedule is urgently.

0 Biser Gatchev-XID over 10 years ago in reply to Eric Cheng1

TI__Guru**** 393215 points

What is the signal level on DDR_CKE in suspend? If there is a Vtt termination resistor on this signal it must be removed.

0 Eric Cheng1 over 10 years ago in reply to Biser Gatchev-XID

Intellectual 320 points

Hi Biser,

Sorry, I am not a hardware developer, so I really don't understand what is Vtt terination resistor.

Please help me double check schematic below, thank you very much.

0 Biser Gatchev-XID over 10 years ago in reply to Eric Cheng1

TI__Guru**** 393215 points

You do have a Vtt regulator, but the termination resistors are not shown on what you posted. These should be on the address/control DDR lines on one end, and tied to VTT_DDR on the other end.

0 Eric Cheng1 over 10 years ago in reply to Biser Gatchev-XID

Intellectual 320 points

Hi Biser,

I think the schematic about DDR3, but I also need you to confirm it. thank you very much.

0 Biser Gatchev-XID over 10 years ago in reply to Eric Cheng1

TI__Guru**** 393215 points

Yes, this is DDR3 and DDR_CKE is not terminated, which is correct. However the 22Ohm termination value is absolutely wrong. These resistors should match the address/control traces impedance, which is typically 50Ohm.

0 Eric Cheng1 over 10 years ago in reply to Biser Gatchev-XID

Intellectual 320 points

Hi Biser,

So your meaning, the root cause of resume from suspend failed is 22ohm, right?

Eric

0 Biser Gatchev-XID over 10 years ago in reply to Eric Cheng1

TI__Guru**** 393215 points

I cannot say but this can be a problem. Is your DDR functioning normally otherwise?

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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am335x resume from suspend mode failed