Public bug reported:

[Impact]
On new systems that facilitate s2idle, we observed the power consumption raises 
higher than long idle does during s2idle with Western Digital PC SN720 NVMe SSD 
SDAPNTW-256G.

Short idle: 5.3
Long idle: 3.0
S2I: 5.07

[Fix]
Windows doesn't put nvme to D3 in modern standby, 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 the WD NVMe, it fixes the power consumption issue with no 
regression. And the power consumption decreases to 1.66W during s2idle.

[Regression Potential]
Low, the patches only applied to specific nvme module, and from our test, the 
system is still stable.

** Affects: hwe-next
     Importance: Undecided
         Status: New

** Affects: linux-oem (Ubuntu)
     Importance: Undecided
     Assignee: AceLan Kao (acelankao)
         Status: In Progress


** Tags: originate-from-1805324 somerville

** Tags added: originate-from-1805324 somerville

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https://bugs.launchpad.net/bugs/1805775

Title:
  PC SN720 NVMe WDC 256GB consumes more power in S2Idle than long idle

Status in HWE Next:
  New
Status in linux-oem package in Ubuntu:
  In Progress

Bug description:
  [Impact]
  On new systems that facilitate s2idle, we observed the power consumption 
raises higher than long idle does during s2idle with Western Digital PC SN720 
NVMe SSD SDAPNTW-256G.

  Short idle: 5.3
  Long idle: 3.0
  S2I: 5.07

  [Fix]
  Windows doesn't put nvme to D3 in modern standby, 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 the WD NVMe, it fixes the power consumption issue with no 
regression. And the power consumption decreases to 1.66W during s2idle.

  [Regression Potential]
  Low, the patches only applied to specific nvme module, and from our test, the 
system is still stable.

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