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

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

On Thu, 2013-12-05 at 14:42 +0100, Christoph Fritz wrote:
> 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, ..?

Update: It has definitely something to do with DDR3. I'll investigate
this further. By the way, is there a TI-Board with DDR3 and working
suspend-resume?

Thanks
  -- Christoph