Bug#886731: linux-image-4.9.0-4-amd64: DKMS sends system in suspend since linux-image-4.9.0-3-amd64

[Ben Hutchings]

On Thu, 2018-01-11 at 12:25 +0100, Marc-Robin Wendt wrote:
> Hello Ben and Michael,
> 
> thanks for taking time. Of course its DPMS. Sorry for the typo.
> 
> Reproducing the bug turns out, it first appears in linux-image-4.9.0-4-
> amd64 and now linux-image-4.9.0-5-amd64.
> 
> When I boot the system from grub with old kernel linux-image-4.9.0-3-
> amd64 or linux-image-4.9.0-2-amd64, behavior is as expected ok, means
> switching off the monitor doesnt trigger suspend of the system.

So are *you* switching off the monitor?  You mentioned DPMS, which is
the way for the display adapter to control the monitor - it doesn't
involve any signalling in the other direction.

And is the monitor attached to a VGA or digital port?  If it's a
digital port, turning off power to the monitor will look exactly the
same as unplugging it...

> Graphic card, see my first mail. Its a Lenovo T430s, so probably NVIDIA
> NVS 5200M inside. Monitor is LG 34UM88C-P.

...and if you have a laptop that is already closed, unplugging the last
external display is *supposed* to trigger suspend by default.  (The
same as when you have the laptop open with no external display, and
then close the laptop.)

But if this happens with the laptop still open, then this might be a
kernel problem with lid switch detection.

Ben.

> Attached is the journalctl output once with linux-image-4.9.0-3-amd64
> booted and once with linux-image-4.9.0-4-amd64.

-- 
Ben Hutchings
If you seem to know what you are doing, you'll be given more to do.

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