On Thu, Nov 24, 2022 at 12:09 AM David E. Box <david.e.box@xxxxxxxxxxxxxxx> wrote: > > Hi You-Sheng, > > On Wed, 2022-11-23 at 18:27 +0800, You-Sheng Yang wrote: > > 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. > > For the patch to work BIOS must allow the OS to control ASPM. If this is not the > case then you will see the message "ACPI FADT declares the system doesn't > support PCIe ASPM, so disable it". Please check for this on the systems that > don't work. If so the only option is a BIOS change to enable it. Thank you. It's exactly what you said. The ADL-M/RPL platforms I have do not support OS PCIe ASPM. > David > > > 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 > > > -- Regards, You-Sheng Yang
