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[61.227.110.150]) by smtp.gmail.com with ESMTPSA id i8-20020a170902c94800b00172fad607b3sm13969212pla.207.2022.11.23.02.27.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Nov 2022 02:27:24 -0800 (PST) Message-ID: <5c766840-e092-45ea-0664-7bbdb78b933a@canonical.com> Date: Wed, 23 Nov 2022 18:27:18 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH V8 0/4] PCI: vmd: Enable PCIe ASPM and LTR on select hardware Content-Language: en-US To: "David E. Box" Cc: michael.a.bottini@intel.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, me@adhityamohan.in, rafael@kernel.org, hch@infradead.org, robh@kernel.org, bhelgaas@google.com, kw@linux.com, lorenzo.pieralisi@arm.com, nirmal.patel@linux.intel.com, jonathan.derrick@linux.dev References: <20221103021822.308586-1-david.e.box@linux.intel.com> From: You-Sheng Yang In-Reply-To: <20221103021822.308586-1-david.e.box@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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