Re: [PATCH] ARM: OMAP2+: omap_device: drop broken RPM status update from suspend_noirq

From: Tony Lindgren
Date: Tue Jul 25 2017 - 03:11:01 EST


* Grygorii Strashko <grygorii.strashko@xxxxxx> [170724 15:17]:
> My personal thought here is that removing of pm_runtime_set_active() will not fix
> root cause of the problem, but rather hide it :( and, probably, real fix will be
> to update USB framework to ensure that all suspend devices are also PM runtime suspend
> (not sure how) or add few more pm_suspend_ignore_children() calls
> (for example as I've tried to do in [2], but this was unfinished).
>
> I've found very simple steps to reproduce suspend failure on am335x-evm (should also
> work on BBB) - do below sequence with USB device plugged:
>
> echo platform > /sys/power/pm_test
> echo 1 > /sys/power/pm_print_times
> [ echo 0 > /sys/module/printk/parameters/console_suspend ]
> echo mem > /sys/power/state
>
> [ 95.499685] calling 47400000.usb+ @ 733, parent: ocp
> [ 95.504818] am335x-usb-childs 47400000.usb: runtime PM trying to suspend device but active child
> [ 95.513750] am335x-usb-childs 47400000.usb: omap device suspend failure 0
>
> Below I've attached possible patch which converts OMAP device to
> use pm_runtime_force_suspend/resume().

It seems to almost work for my PM test cases.. It seems that serial console
somehow won't get restored after suspend/resume cycle on omap3 though.

The system enters off mode during suspend, and wakes up properly so I can
ssh to it after resume. But the serial console no longer works after resume.
This is with 8250-omap driver.

Regards,

Tony