This bug is missing log files that will aid in diagnosing the problem.
While running an Ubuntu kernel (not a mainline or third-party kernel)
please enter the following command in a terminal window:
apport-collect 1950042
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.
** Changed in: linux (Ubuntu)
Status: New => Incomplete
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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:
New
Status in linux-oem-5.13 package in Ubuntu:
New
Status in linux-oem-5.14 package in Ubuntu:
New
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:
Confirmed
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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