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Wed, 06 May 2026 19:51:59 -0700 (PDT) Message-ID: <26361f34-f24a-4289-bfc6-799b8f189fc1@gmail.com> Date: Wed, 6 May 2026 19:51:57 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] PCI/ASPM: Don't reconfigure ASPM entering low-power state To: Bjorn Helgaas , "Carlos Bilbao (Lambda)" Cc: bhelgaas@google.com, eduardo.habkost@lambdal.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, bilbao@vt.edu References: <20260506181012.GA803978@bhelgaas> Content-Language: en-US From: Carlos Bilbao In-Reply-To: <20260506181012.GA803978@bhelgaas> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hey Bjorn. On 5/6/26 11:10, Bjorn Helgaas wrote: > On Mon, Apr 27, 2026 at 09:01:04PM -0700, Carlos Bilbao (Lambda) wrote: >> From: Carlos Bilbao >> >> Reconfiguring ASPM when a device transitions to low-power state can enable >> L1.1/L1.2 substates on the PCIe link at a time when the device is sleeping >> and may be unable to exit them. ASPM should be reconfigured on D0 entry >> (resume), not on the way down. >> >> pci_set_low_power_state() calls pcie_aspm_pm_state_change() after writing >> D3hot to PCI_PM_CTRL. pcie_aspm_pm_state_change() resets link->aspm_capable >> to link->aspm_support and then calls pcie_config_aspm_path(), which can >> enable ASPM L1.1/L1.2 substates on the PCIe link. If the device cannot >> recover the link from L1.2 while in D3hot, subsequent config space reads >> return 0xFFFF ("device inaccessible") and pci_power_up() fails with message >> "Unable to change power state from D3hot to D0, device inaccessible". > Carlos, do you have a few lines of dmesg showing this issue that we > could quote to help people match the issue with this fix? Thank you for reviewing this. Only the error message: [160459.607156] vfio-pci 0000:5d:00.0: Unable to change power state from D3cold to D0, device inaccessible Thanks, Carlos