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Wed, 27 May 2026 01:15:03 +0000 Date: Tue, 26 May 2026 18:14:59 -0700 From: Alison Schofield To: Chen Pei CC: , , , , , , , , , , Subject: Re: [PATCH 0/2] ACPI/PCI/CXL: Enforce _DEP ordering between ACPI0016 and ACPI0017 Message-ID: References: <20260526025118.38935-1-cp0613@linux.alibaba.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260526025118.38935-1-cp0613@linux.alibaba.com> X-ClientProxiedBy: BY5PR03CA0010.namprd03.prod.outlook.com (2603:10b6:a03:1e0::20) To DS4PPF0BAC23327.namprd11.prod.outlook.com (2603:10b6:f:fc02::9) Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS4PPF0BAC23327:EE_|CH3PR11MB8659:EE_ X-MS-Office365-Filtering-Correlation-Id: f88ff4d0-5d5c-44b2-7274-08debb8d6165 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016|11063799006|6133799003|56012099006|22082099003|18002099003; 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ACPI0016 is not on acpi_honor_dep_ids[], so even when ACPI0017 > declares _DEP on it, acpi_dev_ready_for_enumeration() bypasses > the dep_unmet check and lets cxl_acpi probe early. > > On x86 the bug is usually masked by link order (acpi_pci_root is > built in and probed before cxl_acpi). On architectures like RISC-V > that ordering is not guaranteed, so the standard ACPI _DEP mechanism > must actually work. > > This series fixes both sides and the two patches must be applied > together; applying only patch 2 would prevent cxl_acpi from ever > probing on ACPI0016 systems, because the supplier would never clear > the dependency. > > Patch 1 makes acpi_pci_root_add() clear _DEP on the supplier once > the PCI root bus has been added. > Patch 2 adds ACPI0016 to acpi_honor_dep_ids[] so the dependency > declared by ACPI0017 is enforced. > > The approach in this series follows the discussion of an earlier > posting: > https://lore.kernel.org/linux-cxl/20260514023238.49984-1-cp0613@linux.alibaba.com/ > > Chen Pei (2): > ACPI: PCI: clear _DEP dependencies after PCI root bridge attach > ACPI: scan: honor _DEP for ACPI0016 PCI/CXL host bridge For the set: Tested-by: Alison Schofield Reviewed-by: Alison Schofield