{"id":2229302,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2229302/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260428040104.78524-1-carlos.bilbao@kernel.org/","project":{"id":28,"url":"http://patchwork.ozlabs.org/api/1.1/projects/28/?format=json","name":"Linux PCI development","link_name":"linux-pci","list_id":"linux-pci.vger.kernel.org","list_email":"linux-pci@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260428040104.78524-1-carlos.bilbao@kernel.org>","date":"2026-04-28T04:01:04","name":"PCI/ASPM: Don't reconfigure ASPM entering low-power state","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"0694b0082a5436e00b0f201c007b6991ad5ca68a","submitter":{"id":93050,"url":"http://patchwork.ozlabs.org/api/1.1/people/93050/?format=json","name":"Carlos Bilbao (Lambda)","email":"carlos.bilbao@kernel.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260428040104.78524-1-carlos.bilbao@kernel.org/mbox/","series":[{"id":501759,"url":"http://patchwork.ozlabs.org/api/1.1/series/501759/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/list/?series=501759","date":"2026-04-28T04:01:04","name":"PCI/ASPM: Don't reconfigure ASPM entering low-power state","version":1,"mbox":"http://patchwork.ozlabs.org/series/501759/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2229302/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2229302/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=aeoHnv+/;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c15:e001:75::12fc:5321; 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a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1777348871; cv=none;\n b=iGGU/duC5Wv7zH/b4SefTFGuf7+fQLwkDDvauriZQ9DNhl/kLE8zLCVIjzl2oPzdbigF4xpYuM5CYXyzhpV+ZVjYiDynu5KLgqu7kilXnJ0ynqwk7wZKN8pi6Xr36E1/JLFbrokLhA11KLlUUTgNgtZoWgfaTXJiE9T94mTc84M=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1777348871; c=relaxed/simple;\n\tbh=6yJDQrFYOnSimHYpjK9gZ6lZp3jY/9xvbZuj1IWjkWE=;\n\th=From:To:Cc:Subject:Date:Message-ID:MIME-Version;\n b=Im+ib5GJ4wNvKKAJNm4po8IqLeZGK9SPJLhp6WlpTrK2gyM/MnZLnPei8ph3eAIC36OQXze99vukRpX+czN+P4efCmX0DlA+nMdY72SW9q18QcaQ6tbCQfnZZkCV0tVS+ddaF3m755ho8h7oMKeaiciUv58BG5ifqYMYWA3cFTc=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=aeoHnv+/; arc=none smtp.client-ip=10.30.226.201","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1777348871;\n\tbh=6yJDQrFYOnSimHYpjK9gZ6lZp3jY/9xvbZuj1IWjkWE=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=aeoHnv+/fK/IjbEEmCfCOIYlwLOzgRnqb6yUYHIwx3hc8aLdXi6iypqDi/R6K+PrI\n\t Dlj7A68pqvo1SAiEYzMJvZXkt5CcSyHohtUe5jhjfIOV3TFCtkU93RO8I/vrjPHFSN\n\t 2KOR4JSSIGmVez3Jlghd4MQ1U+02WTCnxPi1pIWv1l/CCFC7vrjZ/FTdbckU5hWq7t\n\t 4h3+wlPeSrxrKr345oGkg4YaxkiCmHRbLE0LIctAUA26DLGcBMAWpIaza+jIvXj/zc\n\t K2PclFDbOAgD1Cc0xrtpSzvut1y8KkmPMyXs+DCbwc6SP3zQiANDTgZtpdAQf2eK9u\n\t GxbQqKWCwpTVw==","From":"\"Carlos Bilbao (Lambda)\" ","To":"bhelgaas@google.com","Cc":"eduardo.habkost@lambdal.com,\n\tlinux-pci@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org,\n\tbilbao@vt.edu,\n\tCarlos Bilbao ","Subject":"[PATCH] PCI/ASPM: Don't reconfigure ASPM entering low-power state","Date":"Mon, 27 Apr 2026 21:01:04 -0700","Message-ID":"<20260428040104.78524-1-carlos.bilbao@kernel.org>","X-Mailer":"git-send-email 2.43.0","Precedence":"bulk","X-Mailing-List":"linux-pci@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit"},"content":"From: Carlos Bilbao \n\nReconfiguring ASPM when a device transitions to low-power state can enable\nL1.1/L1.2 substates on the PCIe link at a time when the device is sleeping\nand may be unable to exit them. ASPM should be reconfigured on D0 entry\n(resume), not on the way down.\n\npci_set_low_power_state() calls pcie_aspm_pm_state_change() after writing\nD3hot to PCI_PM_CTRL. pcie_aspm_pm_state_change() resets link->aspm_capable\nto link->aspm_support and then calls pcie_config_aspm_path(), which can\nenable ASPM L1.1/L1.2 substates on the PCIe link. If the device cannot\nrecover the link from L1.2 while in D3hot, subsequent config space reads\nreturn 0xFFFF (\"device inaccessible\") and pci_power_up() fails with message\n\"Unable to change power state from D3hot to D0, device inaccessible\".\n\nThis was observed on NVIDIA H100 SXM5 GPUs bound to vfio-pci when Linux\nruntime PM suspends them to D3hot: the GPU becomes permanently inaccessible\nand disappears from the PCIe bus.\n\nThe call to pcie_aspm_pm_state_change() in pci_set_low_power_state() was\nrestored by commit f93e71aea6c6 (\"Revert \"PCI/ASPM: Remove\npcie_aspm_pm_state_change()\"\"), which reverted\ncommit 08d0cc5f3426 (\"PCI/ASPM: Remove pcie_aspm_pm_state_change()\").\nThe revert was necessary because the\nremoval broke suspend/resume on certain platforms that required ASPM to be\nreconfigured on D0 entry. However, the revert restored the call in both\npci_set_full_power_state() (D0 entry) and pci_set_low_power_state()\n(low-power entry).\n\nOnly the D0-entry call is needed to fix the suspend/resume regression. The\nlow-power-entry call is harmful: reconfiguring ASPM immediately after\nputting a device into D3hot can enable link substates that the device or\nplatform cannot exit while the device is sleeping.\n\nRemove the pcie_aspm_pm_state_change() call from pci_set_low_power_state().\nASPM will still be reconfigured correctly when the device returns to D0 via\npci_set_full_power_state().\n\nFixes: f93e71aea6c6 (\"Revert \"PCI/ASPM: Remove pcie_aspm_pm_state_change()\"\")\nLink: https://lore.kernel.org/r/20240102232550.1751655-1-helgaas@kernel.org\nSigned-off-by: Carlos Bilbao (Lambda) \n---\n drivers/pci/pci.c | 3 ---\n 1 file changed, 3 deletions(-)","diff":"diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c\nindex b2ccb8e122f2..8b47887019f9 100644\n--- a/drivers/pci/pci.c\n+++ b/drivers/pci/pci.c\n@@ -1542,9 +1542,6 @@ static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state, bool\n \t\t\t\t pci_power_name(dev->current_state),\n \t\t\t\t pci_power_name(state));\n \n-\tif (dev->bus->self)\n-\t\tpcie_aspm_pm_state_change(dev->bus->self, locked);\n-\n \treturn 0;\n }\n \n","prefixes":[]}