** Changed in: linux-oem-5.14 (Ubuntu Focal)
Status: Confirmed => Fix Committed
** Changed in: linux-oem-5.14 (Ubuntu)
Status: New => Invalid
** Changed in: linux-oem-5.13 (Ubuntu)
Status: New => Invalid
** Changed in: linux-oem-5.10 (Ubuntu)
Status: New => Invalid
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https://bugs.launchpad.net/bugs/1950042
Title:
Let NVMe with HMB use native power control again
Status in HWE Next:
New
Status in linux package in Ubuntu:
Incomplete
Status in linux-oem-5.10 package in Ubuntu:
Invalid
Status in linux-oem-5.13 package in Ubuntu:
Invalid
Status in linux-oem-5.14 package in Ubuntu:
Invalid
Status in linux source package in Focal:
Won't Fix
Status in linux-oem-5.10 source package in Focal:
Confirmed
Status in linux-oem-5.13 source package in Focal:
Confirmed
Status in linux-oem-5.14 source package in Focal:
Fix Committed
Status in linux source package in Hirsute:
Confirmed
Status in linux-oem-5.10 source package in Hirsute:
Invalid
Status in linux-oem-5.13 source package in Hirsute:
Invalid
Status in linux-oem-5.14 source package in Hirsute:
Invalid
Status in linux source package in Impish:
Confirmed
Status in linux-oem-5.10 source package in Impish:
Invalid
Status in linux-oem-5.13 source package in Impish:
Invalid
Status in linux-oem-5.14 source package in Impish:
Invalid
Bug description:
Impact]
NVMe with HMB may still do DMA during suspend, so there was a commit
that put the NVMe to PCI D3 during suspend to prevent DMA activities.
However, this makes them consumes much more power because modern NVMe
requires to stay at PCI D0 to make its natve power control work.
[Fix]
Instead of put the NVMe to PCI D3 and reset it afterward, simply disable
HMB and re-enable HMB, for suspend and resume respectively.
[Test]
On affected system, Intel SoC can only reach PC3 during suspend.
With the SRU applied, the Intel SoC can reach PC10 and SLP_S0 and use
significant less power.
[Where problems could occur]
The original approach, i.e. disable NVMe and put it to PCI D3 to prevent
DMA activies, was just a precaution. There wasn't any case that
indicates it happens in practice.
This is a different approach to the same problem, which is a theoretical
problem.
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