-----Original Message-----
From: Jérôme de Bretagne [mailto:jerome.debretagne@gmail.com]
Sent: Thursday, June 8, 2017 6:44 PM
To: Limonciello, Mario <redacted>
Cc: ACPI Devel Maling List <redacted>; Linux PM <linux-
pm@vger.kernel.org>; Rafael J. Wysocki [off-list ref]; Andy Shevchenko
[off-list ref]; Darren Hart [off-list ref];
Srinivas Pandruvada [off-list ref]; Mika Westerberg
[off-list ref]
Subject: Re: [PATCH 0/3] ACPI / sleep: Support power button wakeup from S2I on
recent Dell laptops

Hi Mario,

quoted

quoted

Here is some feedback for Dell Latitude 7275, as suggested by Srinivas
in https://bugzilla.kernel.org/show_bug.cgi?id=195897#c15 .

For some context on that model, suspend-to-RAM is not safe as the
system hangs (raised in the above bug report). I'm wondering if this
is expected somehow, due to S3 not being supported on that model, as
discussed for the XPS 13 9365. Maybe Mario or someone else from Dell
would be able to confirm this point.

The Latitude 7275 was not a machine that was tested with Linux during
development.
This machine shipped with Windows 8, right?

I've read that this machine shipped at first with the option to have it either
with Windows 10 or Windows 8.1. Mine came with Windows 10.

quoted

I believe this machine also supports Connected Standby (the precursor
to Modern Standby that behaves very similarly).

I've in fact found some WinHEC slides stating that it was among the first
systems to support Modern Standby, here for reference:
https://f.ch9.ms/public/WinHEC/06_WinHECDec2016-
DesigningPowerEfficient_v02.pptx

quoted

I have an ask out to someone who can confirm that.	

Thanks. I'm hoping there's a chance to make it work with suspend-to-RAM
on Linux still, in addition to suspend-to-idle, by fixing the current hang.

I got a response back that confirmed that this machine only is supported
with CS/MS.  I would not expect S3 to work properly.

Even if S3 is part of the ACPI namespace, the behavior that Windows follows
is that S3 is not offered when the low power idle bit is set in FADT.

I know that the current behavior in Linux does not review low power idle
bit to determine whether to offer S2I or S3 so I'm inquiring if we can remove
S3 from a future BIOS update on this platform to let Linux work better
even though we don't ship this platform with Linux.

For now I would recommend that you focus efforts exclusively on making
S2I work, and ignore S3 problems.


Regarding the long button press necessary to wake the system, you might
not have seen the discussions and threads that explain this.
Essentially the EC is sending a SCI when you press the button press, and it's
supposed be interpreted by a driver and that driver would wake the system.
(intel-hid or intel-vbtn on Linux).
If you long press the power button, after a certain period of  time it uses
a GPIO to wake up the system.

It's unclear to me exactly when you tested s2idle-dell-test.
Can you re-test with Rafael's newest submissions and changes to s2idle-dell-test
committed 28 hours ago?
You'll still have to add your system to the DMI whitelist for the last patch
but he has reworked a bunch of related wakeup code that has also changed.

Thanks,