Public bug reported: [Impact] PCIe links behind VMD may not be able to reach ASPM L1.2, because PCIe Link Tolenrence Reporting doesn't get programmed with a sensible value.
[Fix] Temporarily hardcode LTR value, which is used by Windows, for NVMe devices behind VMD. [Test] With the patch applied, PCIe links can reach ASPM L1.2, hence the entire Intel SoC can reach deeper power saving state. [Regression Potential] This patch targets specifically Intel Tigerlake VMD bridges, so there won't be any regression since they are not on the market yet. ** Affects: linux (Ubuntu) Importance: Medium Status: Confirmed ** Affects: linux-oem-5.6 (Ubuntu) Importance: Undecided Status: New ** Affects: linux (Ubuntu Focal) Importance: Undecided Status: Won't Fix ** Affects: linux-oem-5.6 (Ubuntu Focal) Importance: Medium Status: Confirmed ** Affects: linux (Ubuntu Groovy) Importance: Medium Status: Confirmed ** Affects: linux-oem-5.6 (Ubuntu Groovy) Importance: Undecided Status: Invalid ** Also affects: linux (Ubuntu Groovy) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Focal) Importance: Undecided Status: New ** Also affects: linux-oem-5.6 (Ubuntu) Importance: Undecided Status: New ** Changed in: linux (Ubuntu Focal) Status: New => Won't Fix ** Changed in: linux-oem-5.6 (Ubuntu Groovy) Status: New => Won't Fix ** Changed in: linux-oem-5.6 (Ubuntu Groovy) Status: Won't Fix => Invalid ** Changed in: linux (Ubuntu Groovy) Importance: Undecided => Medium ** Changed in: linux-oem-5.6 (Ubuntu Focal) Importance: Undecided => Medium ** Changed in: linux-oem-5.6 (Ubuntu Focal) Status: New => Confirmed ** Changed in: linux (Ubuntu Groovy) Status: New => Confirmed -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1896598 Title: Enable LTR for endpoints behind VMD Status in linux package in Ubuntu: Confirmed Status in linux-oem-5.6 package in Ubuntu: New Status in linux source package in Focal: Won't Fix Status in linux-oem-5.6 source package in Focal: Confirmed Status in linux source package in Groovy: Confirmed Status in linux-oem-5.6 source package in Groovy: Invalid Bug description: [Impact] PCIe links behind VMD may not be able to reach ASPM L1.2, because PCIe Link Tolenrence Reporting doesn't get programmed with a sensible value. [Fix] Temporarily hardcode LTR value, which is used by Windows, for NVMe devices behind VMD. [Test] With the patch applied, PCIe links can reach ASPM L1.2, hence the entire Intel SoC can reach deeper power saving state. [Regression Potential] This patch targets specifically Intel Tigerlake VMD bridges, so there won't be any regression since they are not on the market yet. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1896598/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp