** Also affects: linux (Ubuntu Bionic)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Cosmic)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1801875
Title:
Power consumption during s2idle is higher than long idle(sk hynix)
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
New
Status in linux source package in Cosmic:
New
Bug description:
[Impact]
On some Dell XPS models, we observed the power consumption raises higher than
long idle does during s2idle with sk hynix nvme.
C2:
Short idle: 4
Long idle: 1
S2I: 3.7
S5: 0.19
C3:
Short idle: 7.2
Long idle: 4.5
S2I: 6.22
S5: 0.18
C5:
Short idle: 6.5
Long idle: 1
S2I: 2.88
S5: 0.18
[Fix]
From SK hynix FE, MS Windows doesn't put nvme to D3, and uses its own APST
feature to do the power management. To leverage its APST feature during s2idle,
we can't disable nvme device while suspending, too.
So, here is what we did on the driver, 1. prevent nvme from entering D3, 2.
prevent nvme from being disabled when suspending.
[Test]
Verified on different XPS machines with different sk hynix nvme disks, it
fixes the power consumption issue with no regression. And the power consumption
drops to 0.77W during s2idle.
[Regression Potential]
Low, the patches only applied to specific nvme module, and from our test, the
system is still stable.
[Misc]
This issue should be fixed by the firmware, and we're pushing sk hynix to fix
it. But before sk hynix find out how to solve it, we have to preserve these
commits in our kernel for a while.
BTW, the patches use pm_suspend_via_s2idle() function from below commit which
is still under reviewing.
https://lists.ubuntu.com/archives/kernel-team/2018-October/096141.html
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