ACK: [PATCH 0/1][SRU][B][C][D][OEM-B]PC SN720 NVMe WDC 256GB consumes more power in S2Idle than during long idle

[Kai Heng Feng]

> On Nov 29, 2018, at 3:44 PM, AceLan Kao <acelan.kao at canonical.com> wrote:
> 
> To avoid conflicts, this patch assumes below commits have been applied
> on top of master-next branch on Bionic, Cosmic, and Disco kernel,
> since both patches modify the same files on the same position for the
> same issue.
> https://lists.ubuntu.com/archives/kernel-team/2018-November/096832.html
> 
> BugLink: https://bugs.launchpad.net/bugs/1805775
> 
> [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.
> 
> AceLan Kao (1):
>  SAUCE: pci/nvme: prevent WDC PC SN720 NVMe from entering D3 and being
>    disabled
> 
> drivers/nvme/host/pci.c | 2 ++
> drivers/pci/quirks.c    | 1 +
> 2 files changed, 3 insertions(+)

Acked-by: Kai-Heng Feng <kai.heng.feng at canonical.com>

> 
> -- 
> 2.17.1
> 
> 
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