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Wed, 23 Sep 2026 05:40:50 -0700 From: Jamie Nguyen To: Sudeep Holla CC: Jamie Nguyen , Lorenzo Pieralisi , Hanjun Guo , Catalin Marinas , Will Deacon , "Rafael J. Wysocki" , Len Brown , Dat Mach , , , Subject: Re: [PATCH v2 0/3] ACPI: arm64: FFH Operation Region support for FF-A (offset 2) Date: Wed, 23 Sep 2026 05:40:50 -0700 Message-ID: <20260923124050.3270801-1-jamien@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260922-exuberant-earwig-of-opportunity-4fecff@sudeepholla> References: <20260901192906.133670-1-jamien@nvidia.com> <20260922-purring-fennec-of-exercise-bbce5e@sudeepholla> <20260922155211.676134-1-jamien@nvidia.com> <20260922-exuberant-earwig-of-opportunity-4fecff@sudeepholla> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN1PEPF00018547:EE_|MW6PR12MB8836:EE_ X-MS-Office365-Filtering-Correlation-Id: 5eff6a1c-c33e-426d-0aa7-08df196ff3d5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700016|82310400026|7416014|376014|23010399003|11063799006|56012099006|10067099003|6133799003|22082099003|18002099003|4143699003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(36860700016)(82310400026)(7416014)(376014)(23010399003)(11063799006)(56012099006)(10067099003)(6133799003)(22082099003)(18002099003)(4143699003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: BAFkMSYp++sftzVKKTePpAn6A97R2nvjzWRIVPqzAhuJI/rCB/EoXKiyl+i400n9Bi/QfFuP8q6G9LZ62OkImg2u40lzYlYj65/u/tgUAjPEP5ZRhweXznXkl3W32SlUANEu62yvDdL+dxMH/YcYiU7UNOomOBt6KupOlHUuxNWyip+YMSCJaS2lE9+bEPuJcOwZgNDGdojVv1hmAZRG1AtU7DtxBy4SSVzC24C26qPjsv92Lt8eZUmsH3YEkL1tpIFT7/uFuDtR23b4TCIVF/lAhvZ+oGc7OfyfcS938mm1KeGT368yoBNimxvs1TUymTzA7/XOTVdmPXF9mFDQfv+3fqUtctvrP59mjdWBiUzCxsUlEHeMhGHpbhhoxUqbP0Pbn061S9CDIXlCEMgRepv43u+G+c+65rj1j+WB7GztQfCIfuGZd90+G1VHguJ5 X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Sep 2026 12:41:13.0956 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5eff6a1c-c33e-426d-0aa7-08df196ff3d5 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN1PEPF00018547.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW6PR12MB8836 On Tue, Sep 22, 2026 at 07:06:02PM +0100, Sudeep Holla wrote: > Equally ugly. FF-A spec doesn't talk about ACPI FFH, so it doesn't > belong in FF-A driver. Okay -- I'll move the ACPI-specific handling into ffh.c. > So if on a platform, ASL has FFH with offset 2, we fail if FF-A driver > fails to initialise ? What if this FFH offset 2 is used in some other > device methods that need to be executed before FF-A module is inserted ? > We pull that device down as well ? Is that acceptable ? You're right. With the current registration, offset 2 may be unavailable during initial enumeration or before module load. That's not suitable for AML. > There is no state management with simple FFA_MSG_SEND_DIRECT_REQ2, it is > synchronous send request if you look at it along wih offset 0/1 and > without FF-A driver knowledge. The request itself is synchronous and register-only. But the whole operation still shares FF-A state: version negotiation must be coordinated with other FF-A use, and X1 == 0 needs UUID lookup. It looks like FFA_PARTITION_INFO_GET_REGS is optional at the Non-secure physical instance according to DEN0077A Table 13.1. As such, I believe a portable implementation would need the shared RX/TX buffers. For example, if X1 is zero and that ABI is unavailable, UUID lookup would need to fall back to FFA_PARTITION_INFO_GET, whose results are returned through the caller's RX buffer.