[Bug] am33xx: Basic suspend resume support: Doesn't resume

[Christoph Fritz <chf.fritz@googlemail.com>]

Hi,

 I'm having here a custom am335x board with DDR3 equipped trying to
setup suspend/resume support. I have tested this with the ancient
TI-PSP-3.2 Kernel and current 3.13-rc plus some pm patches.

Problem: After suspending the device, it doesn't resume (freeze):

echo "mem" > /sys/power/state
[  103.020845] PM: Syncing filesystems ... done.
[  103.055549] Freezing user space processes ... (elapsed 0.003 seconds) done.
[  103.066696] Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done.
[  103.077506] PM: Sending message for entering DeepSleep mode
[  103.099896] PM: suspend of devices complete after 11.951 msecs
[  103.110894] PM: late suspend of devices complete after 4.659 msecs
[  103.122599] PM: noirq suspend of devices complete after 5.032 msecs

As a wakeup source I'm currently using gpio0_12.

Triggering the reset button (am335x-pin: WARMRSTn) in suspend-mode has
no effect, which is fine. But after changing the signal on the wakeup
source (here gpio0_12), triggering a reset works fine again.

So it seems to me that somewhere in the wakeup-process is a bug.

Could this be related to DDR3? Apart from that, this custom board here
is pretty similar to the ti-evm board wich works fine.

In oder to test, I've shrunken the kernel to minimal driver support to
sort out as much as possible segfaults in resume functions.

With a view to be able to debug this further, I just ordered an openocd
jtag adapter.

Any comments, ideas, tips, ..?

Thanks
 -- Christoph