linux-kernel - Re: 5.11-rc device reordering breaks ThinkPad rmi4 suspend

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Date:   Mon, 11 Jan 2021 20:42:54 -0800 (PST)
From:   Hugh Dickins <hughd@...gle.com>
To:     Saravana Kannan <saravanak@...gle.com>
cc:     Hugh Dickins <hughd@...gle.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Thierry Reding <treding@...dia.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Vincent Huang <vincent.huang@...synaptics.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Andrew Duggan <aduggan@...aptics.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: 5.11-rc device reordering breaks ThinkPad rmi4 suspend

On Mon, 11 Jan 2021, Saravana Kannan wrote:
> On Mon, Jan 11, 2021 at 4:44 PM Hugh Dickins <hughd@...gle.com> wrote:
> > On Mon, 11 Jan 2021, Saravana Kannan wrote:
> > >
> > > Did you see this patch change the organization of devices under /sys/devices/?
> > > The rmi* devices need to be under one of the i2c devices after this
> > > patch. Is that not the case? Or is that the case, but you are still
> > > seeing suspend/resume issues?
> >
> > Now that I look, yes, that patch has moved the directory
> > /sys/devices/rmi4-00
> > to
> > /sys/devices/pci0000:00/0000:00:1f.4/i2c-6/6-002c/rmi4-00
> 
> What about child devices of rmi4-00? Does it still have the
> rmi4-00.fn* devices as children? I'd think so, but just double
> checking.

Yes, the patch moved the rmi4-00 directory and its contents.

> 
> >
> > But I still see the same suspend issues despite that.
> 
> Can you please get new logs to see if the failure reasons are still
> the same? I'd think this parent/child relationship would at least
> avoid the "Failed to read irqs" errors that seem to be due to I2C
> dependency.

No, it did not avoid the "Failed to read irqs" error (though my
recollection from earlier failures before I mailed out, is that
that particular error is intermittent: sometimes it showed up,
other times not; but always the "Failed to write sleep mode").

I configured CONFIG_PM_DEBUG=y and booted with pm_debug_messages
this time, dmesgsys.tar attached, contents:

dmesg.rc3	# dmesg of boot and attempt to suspend on 5.11-rc3
sys.rc3		# find /sys | sort | grep -v /sys/fs/cgroup afterwards
dmesg.saravana	# dmesg of boot and attempt to suspend with your patch
sys.saravana	# find /sys | sort | grep -v /sys/fs/cgroup afterwards
dmesg.revert	# dmesg of boot+suspend+resume, rc3 without 5b6164d3465f
sys.revert	# find /sys | sort | grep -v /sys/fs/cgroup afterwards

Not as many debug messages as I was expecting: perhaps you can point
me to something else to tune to get more info out? And perhaps it was
a mistake to snapshot the /sys hierarchy after rather than before:
I see now that it does make some difference.  I filtered out
/sys/fs/cgroup because that enlarged the diffs with no relevance.

Hugh
Download attachment "dmesgsys.tar" of type "APPLICATION/x-tar" (99912 bytes)