Messages in this thread | | | Date | Wed, 23 Nov 2022 18:27:18 +0800 | Subject | Re: [PATCH V8 0/4] PCI: vmd: Enable PCIe ASPM and LTR on select hardware | From | You-Sheng Yang <> |
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Hi David,
On 11/3/22 10:18, David E. Box wrote: > This series adds a work around for enabling PCIe ASPM and for setting PCIe > LTR values on VMD reserved root ports on select platforms. While > configuration of these capabilities is usually done by BIOS, on these > platforms these capabilities will not be configured because the ports are > not visible to BIOS. This was part of an initial design that expected the > driver to completely handle the ports, including power management. However > on Linux those ports are still managed by the PCIe core, which has the > expectation that they adhere to device standards including BIOS > configuration, leading to this problem. > > The target platforms are Tiger Lake, Alder Lake, and Raptor Lake though the > latter has already implemented support for configuring the LTR values. > Meteor Lake is expected add BIOS ASPM support, eliminating the future need > for this work around.
It appears to me that this patch series works only on Tiger Lake. We have tried to revert our current work-arounds in Ubuntu kernels generic-5.15/oem-5.17/oem-6.0/unstable-6.1 and apply this series, the prebuilt kernels can be found in:
https://launchpad.net/~vicamo/+archive/ubuntu/ppa-1996620
However, only TGL can still enter PC10 as before.
ADL-M, RPL platforms will stay in PC3 with vmd LTR set, but ASPM disabled. i915 RC6 blocked, too:
$ sudo cat /sys/kernel/debug/dri/
0/i915_dmc_info ... DC3CO count: 0 DC3 -> DC5 count: 100 DC5 -> DC6 count: 0
> Note, the driver programs the LTRs because BIOS would also normally do this > for devices that do not set them by default. Without this, SoC power > management would be blocked on those platform. This SoC specific value is > the maximum latency required to allow the SoC to enter the deepest power > state. > > This patch addresses the following open bugzillas on VMD enabled laptops > that cannot enter low power states. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=212355 > Link: https://bugzilla.kernel.org/show_bug.cgi?id=215063 > Link: https://bugzilla.kernel.org/show_bug.cgi?id=213717 > > David E. Box (3): > PCI: vmd: Use PCI_VDEVICE in device list > PCI: vmd: Create feature grouping for client products > PCI: vmd: Add quirk to configure PCIe ASPM and LTR > > Michael Bottini (1): > PCI/ASPM: Add pci_enable_link_state() > > drivers/pci/controller/vmd.c | 96 ++++++++++++++++++++++++++---------- > drivers/pci/pcie/aspm.c | 54 ++++++++++++++++++++ > include/linux/pci.h | 7 +++ > 3 files changed, 131 insertions(+), 26 deletions(-) > > > base-commit: 247f34f7b80357943234f93f247a1ae6b6c3a740
Regards, You-Sheng Yang
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