linux-kernel - Re: [PATCH] ARM: OMAP2+: omap_device: drop broken RPM status update from suspend

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Message-ID: <9b846eee-4e44-6909-60d8-99ee86e6a212@ti.com>
Date:   Tue, 25 Jul 2017 12:41:27 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Tony Lindgren <tony@...mide.com>
CC:     Johan Hovold <johan@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Dave Gerlach <d-gerlach@...com>,
        Kevin Hilman <khilman@...libre.com>,
        Nishanth Menon <nm@...com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH] ARM: OMAP2+: omap_device: drop broken RPM status update
 from suspend_noirq



On 07/25/2017 03:56 AM, Tony Lindgren wrote:
> * Tony Lindgren <tony@...mide.com> [170725 00:11]:
>> * Grygorii Strashko <grygorii.strashko@...com> [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.
> 
> And FYI, on omap4 this produces a bunch of L3 irq errors on suspend.
> 

Ok. This was a risky change even if it looks obvious :(

-- 
regards,
-grygorii