In this blog post I want to summarize my investigations about problems concerning suspend with my lenovo t460 notebook. (Note: This problem seems to also exists with the lenovo T460s notebooks. More information about debian on the t460 can be found here.)
(The informations here are verified with a debian testing installation with kernel version 4.4. The problems is reported by people using other distributions too.)
What is the problem and how can you reproduce it?
- If the device is on the AC, closing the lid causes the notebook to suspend. This works perfectly – in other words: The notebook wakes up after opening the lid and is usable.
- If the notebook is on battery, closing the lid causes the notebook to freeze. In other words: If I open the lid again, everything is frozen. Not only the UI but I’m also not able to change to TTY1, 2, ..
- Interestingly enough, manually suspending with systemctl suspend works without a glitch.
There is an entry in the kernel bug tracker Bug 113551 – intel_pstate=no_hwp else Thinkpad T460s freezes on lid close on battery power. The bug entry indicates that the problem is also to be found kernel versions up to 4.5.0-rc6. It also looks like the source of the problem is found, patches are being tested. I also filed a debian bug entry for this problem as was suggested to my when asking in the debian IRC channel.
So it seems that newer kernel versions won’t have this problem. There is a workaround till this happens. You can add the intel_pstate=no_hwp parameter to the GRUB_CMDLINE_LINUX_DEFAULT section of the /etc/default/grub file. Attention: Don’t forget to run update-grub after every change to this file. Also: This may cause your notebook to use more power – the battery may empty itself faster.
I will try to update this blog post after more information, changes in the status of this problem occur. I maybe even try to patch the debian kernel with a patch and test if this helps to fix the suspend problem.
Update 2016-04-28: After upgrading to the Debian 4.5.1-1 (2016-04-14) x86_64 GNU/Linux kernel version, the suspend problem is gone. I can close the lid while being on batteries and the notebook is going into suspend and leaves it correctly.