From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CO1PR03CU002.outbound.protection.outlook.com (mail-westus2azon11010014.outbound.protection.outlook.com [52.101.46.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3666A2857EE for ; Tue, 2 Jun 2026 14:55:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.46.14 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780412147; cv=fail; b=eiFUF9pX8G8W2ZSHvVbmXsq1xZR8zs7B8I4N1Ngg/51ByrGvvt30ToIzl8C8cB7iQ+712w02636DAW+lnn/AkETveE2MX7IIauhDRoAxjM+YWbdK1ecXJ6a2XYbzRLnQo8ssmu7V+BG0ECgOEGwxxOTQSbmyMtJZDX7mh4ZURCk= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780412147; c=relaxed/simple; bh=7db2/THU/MJxP92QyMjiB+VSfXpnWQTTgPzLZCHSObo=; h=Content-Type:Date:Message-Id:From:To:Cc:Subject:References: In-Reply-To:MIME-Version; b=rEAN+ZnRDr0VokJbSaYp/zaqqeuBZWXr1VT37EJQfzWTEp9XqNMKGP+hnnsaAfHaBNMrJMOZdETW+7wf5MNMwkwMpG0HJ1yA9DbGSfO2yvRPX+lYS2eDfwjWY2FnecZbazIDvKy9jHO+jAaY0yHT4TpX43DeNFphCnobSEHC84c= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=Kn53XdIz; arc=fail smtp.client-ip=52.101.46.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="Kn53XdIz" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=D/9k7jZRRyTtsCma9RkuDHGiCURN6mkV9bIBxLkSzMldrwCFhd7YLiSitNOecNBJfrJIvwHWi1XydEVSyg7BLvG295wwcRxIYyK9ZJcT6YP6cnZRVBLSPQJNooBwMr6p34ydAbDXVTHSq1mlrq3y91G5FLOkB8PSmJTX7JUOG1mkoYr8mVMMVGZsqls47QK43sD3VjPChpiu57vB7Exz9gGa7d6vuT8hfZ6ryMTm69qmXqLFe2rYwCOP2W2BM/Fx8S9K8SVbTlcbEX+YwTWcO4Xg0SA7WVxhSoUjTIvrPcVYix51ShdkvSxUBwpHyrl0gerJAp+/8A/MdjZLaq7wcQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=FeKTcp8UUVNwXf+UDS5i9AVJG2qG5JF36/WU/SWnoBI=; b=C9nNBWJwQICABqMUlm6UyyvjWH3eOQVK1/bjJzKty3XgbYKY0MHZivbwi4lvDTkq2MQSOxT4ClyVlWplgBnp0XGYgKSTFxjy04SszE6eS5FxsVzzlqt6u5Z1oSXri8+WiP3DDcMYD9nDmRm6gedPdQlHykRx38ZAw2LwbJxUMGHB4S3w/AlLKJYZ2+/Ia3eG+yS7U7rmg5Xqlh1/nCtZ38EE2r4FVWoDPRT8+kOsgWWOEwCLCJKhVWXMw7q4jVHfLKtRae8E8MwnokMGq3+jW7OufRBgvGvU1zzPj+otvHc5TctivhKqR+w0abY8cpHSqGABplnxT1OibwuCQkjvLQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=FeKTcp8UUVNwXf+UDS5i9AVJG2qG5JF36/WU/SWnoBI=; b=Kn53XdIzY9fY9g5lM2XbrM5nSeibr3yXSJ3h1zF+4FWGx0j3rHGomS3w3EgaKQsmOxNSBfp7Dmbn00z+kpn7UwiaDjRFDiOGg3YwniaWYkENGlzUk4AzlVjxC8AESzw0EIg4gAWRtlJBXhTP3I6vG5DjGovRBhW9Ndw3UdHyw6WZgNHwIjTj4jv9zmT+Fs7TJBcpDeYuz9zx4IrMX7AtmsqQI7bXHUOP+2yE5GlcNM1yd2kdkqWFsfubwHjozamI6vhucC+Sm0QlbHF4elNLdv8NXcJd8us1b86eLzeA0FHbNHbzERyPdumJRz4z3gsfyqnpdEC6Y2jdez4ztxCUUg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) by MN0PR12MB6272.namprd12.prod.outlook.com (2603:10b6:208:3c0::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.92.7; Tue, 2 Jun 2026 14:55:39 +0000 Received: from CH2PR12MB3990.namprd12.prod.outlook.com ([fe80::7de1:4fe5:8ead:5989]) by CH2PR12MB3990.namprd12.prod.outlook.com ([fe80::7de1:4fe5:8ead:5989%4]) with mapi id 15.21.0092.006; Tue, 2 Jun 2026 14:55:38 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 02 Jun 2026 23:55:34 +0900 Message-Id: From: "Alexandre Courbot" To: "Eliot Courtney" Cc: "John Hubbard" , "Danilo Krummrich" , "Timur Tabi" , "Alistair Popple" , "Shashank Sharma" , "Zhi Wang" , "David Airlie" , "Simona Vetter" , "Bjorn Helgaas" , "Miguel Ojeda" , "Alex Gaynor" , "Boqun Feng" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , , "LKML" Subject: Re: [PATCH v12 14/22] gpu: nova-core: Hopper/Blackwell: add FSP falcon EMEM operations References: <20260602032111.224790-1-jhubbard@nvidia.com> <20260602032111.224790-15-jhubbard@nvidia.com> In-Reply-To: X-ClientProxiedBy: TY4P286CA0033.JPNP286.PROD.OUTLOOK.COM (2603:1096:405:2b2::14) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: nova-gpu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PR12MB3990:EE_|MN0PR12MB6272:EE_ X-MS-Office365-Filtering-Correlation-Id: b8d21972-3a61-4f2f-f330-08dec0b70222 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|10070799003|1800799024|7416014|366016|376014|18002099003|4143699003|11063799006|10063799003|22082099003|56012099006; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH2PR12MB3990.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(10070799003)(1800799024)(7416014)(366016)(376014)(18002099003)(4143699003)(11063799006)(10063799003)(22082099003)(56012099006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 2 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Q1grVmE3UEdHOEpLbzZPZ3RWbTZPUFJTbHVNbGlRVXNRNU5XNlVuNFA0d09w?= =?utf-8?B?Rnc1OHV3QzJhemtEaWovam05V1hiNWh2ak40QkhYeXI0ZzJ1UWx5aUQvVHUz?= =?utf-8?B?VjFCc0QvWVBkQ1NxU2hENUhCVFhudmJTMjF4enNSNDZGTTVKRnJjaUJCdi9M?= =?utf-8?B?N2M1T1JCdjBNMUJaODUzMUhlRDNOZGJHVi9CNEZzR3ZZdFNsY1ZHSnQ0Smxn?= =?utf-8?B?MytTYTNMdnVOOHRDWkRoa2twL2lGaXI4MVBnblB0ZkNFd2pPUExsdnBHQmNG?= =?utf-8?B?NjZmZVJPTlpwMEkyR2VLbU92cmZ1cGZPTmlPSGducEhPWVdiWDZBS3lPWjIz?= =?utf-8?B?ZkJJOUwyMGJFTUJrYnEvVTdOUDJ6bnVyR3hybVJFRXM1NENGNUVrOGo5NlJt?= =?utf-8?B?S2JkWmJ6elhJdENFb1IvRDZLVmpJR0l0ODlLdkdjUmhwM3ZwRzVyc0VBcFdJ?= =?utf-8?B?VVh1TXJGMjJEWldNa050TFJjTDZBTThUVzhvRldLZGNMOXIzS2wxZTZsbHJZ?= =?utf-8?B?SDFzakxGQU02eDdxVVBnZmpxNGRYWWp2bHRHNUVrLzFLZHdUbFVjOHdhU1BC?= =?utf-8?B?N3F2V25IcERhdVJMK240MllMcmxKZklXRTRadlllZFNxMWZXdE5IOHdNMitT?= =?utf-8?B?T0FGUkF1T1NQdW1LVHJwZFdwbnlIV2RFY0UyTEV1WDNMZFJRRFlSK0N2Tjkx?= =?utf-8?B?Tng4dHV1QktvSXVockRMbDJkWGdPN3gwekthWmQ4TTB6c0ZuYkFVY0Q3Rlg0?= =?utf-8?B?Zk9GMzFnb012b0RNN1BJTjFMNWdPeXpLZ2RWNGxkajJKc0p2cHdjeWdIZk9G?= =?utf-8?B?ZGxxWmNyeWpEdVJxMThwR281Mm1ZU3M3UWlmcUYybWwweXF2V29SSThrYzZo?= =?utf-8?B?cDVoVkxVaFVUb2E3TW9leE0rYlRGT2svaHhwdVpOZ3FsK1FkZi9OOEt0ZFcw?= =?utf-8?B?TGdJZnRmcUg4Qkdqc05DelpKbEUvc1pnQjI3VHNFeFVjQ1VXNW5mVm8vK2x6?= =?utf-8?B?d1hQZDl5NXdkbkFnaVR3RkN1NC82U0tjMkc5UVN6QjVrL2ZzOFRlVkxZT2tI?= =?utf-8?B?UW1KSFhoaTMvVjQySGxrMjA3SGhGK29Sb01YT0xYRlQvY0ZuMHg3RlJCbHl2?= =?utf-8?B?dkFTRndPS215aDlDankwSVNtaWlnTmIzT3FyM20xVWZmcHN5TVZxMi9NdzM1?= =?utf-8?B?VTVJVHRhVHI0QVJyWHVvZ1pZdDZJbW5EVzBJeFZHSzZjR2hSNzdvb1ZKbWhR?= =?utf-8?B?Wmx5UGxQTWpETXJKS0FWbDRNYzl3bUJxZk8vdGVBYUlqcTF1eWtOcWp4eFpq?= =?utf-8?B?ejdmN1pXaVdobDQ3MHYxYzREUzl5TEk4VGE0Yi80eW9zTWNFcEY3K1RVQ0lr?= =?utf-8?B?RlBOZ0xmL3ZDYkRjbUhwenFYY1Y5bDJxUWk2VUhBZml0K2VLelNtMC9VV0tX?= =?utf-8?B?UGhUcHhxZ2VSSTcwd1hObE5tWWs3S3lZb2g4WkZ0ZGZRYi9JcU0xU1hVaEI5?= =?utf-8?B?M2tBNG9BQzlESm5jVkYvOEx6Z0Z6TjNtSjVnTkE5RkJ3d0cwZnI5L216ZjFH?= =?utf-8?B?alAvUUR5M2UyQktDOGRYM08wcGthTmYreEc4WDlZQ1RVNU5UUDBSR3FDNXJi?= =?utf-8?B?NEcyUjZYMWs2SnVpNHZzMnVZRTZqa2Y0STFYa0xsK1Nma0JZYmd2R2NreGdI?= =?utf-8?B?eExzY096NTNVbHNoTEMzczJXVGZCWWhlSStGZStmTGdRdjlNaXVUR2dRZDBC?= =?utf-8?B?UHYrVEkveFZTbWQ3M08wbEo0bmhCenpDZnFySU4yV1d3NGpFeXZpdkVHckg2?= =?utf-8?B?bDFCQ3dJTUszSUlTV3daUXo2UW9TZ2lqQklubEtzaTg3RUZqZStmeWF2Qzdn?= =?utf-8?B?cWZiUkZ3YVNmelJzZWpRekxUNFVtZ0lUTkVvT2UrSHJKRXFQajRlNmlhOGpi?= =?utf-8?B?YWhoV04yNjdYUHZ2bmVzeGcvUm5CUnFFWTM4T2VacU9aTnVZZzhXMS9ETUxY?= =?utf-8?B?UDMyT3pqdCtHellTYzBxZHU0R0VReU5XTGxKa0gzQmlEcmovMVFVcVBlclJq?= =?utf-8?B?UDJWNmJXaFRTajJUY3FpSTdtNHpUaHZWc0dQNFNlbERKOXVDRkhlRklsakV0?= =?utf-8?B?NjZwRVY0aUU4amx4TmhvZkowRkZtVUdvcHdESWFIVHNlVHZRRmRRekZaVy9L?= =?utf-8?B?aGl5dzBZQWk2RitTWHF1ajY3OEhkYlFBODRqbkpFdlBmTys4WVdhQ1daQkpj?= =?utf-8?B?RFhFclNQQ0t0dE1YYWRMa2RNYkVHcUdJZzhQVUdxRGF6SVVXZVh1SjdGQVdz?= =?utf-8?B?Q2xOYW4wZy91K2JaN3NxVy8yeWJsMSs0c0hXQkRCTnc5U0ZSWFFGVXpBcVFi?= =?utf-8?Q?9dHPrixubuO6kAyi0QDxxN8JhWs5it7GzNsD/D+hSl6FR?= X-MS-Exchange-AntiSpam-MessageData-1: enY7LRD6w1nYrA== X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b8d21972-3a61-4f2f-f330-08dec0b70222 X-MS-Exchange-CrossTenant-AuthSource: CH2PR12MB3990.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Jun 2026 14:55:38.6859 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ebFfxKrydU5gE48AOih/4uFx1hDCmixLsz3+kRb+na/+1s0NHHVZlzhKRFVANuEDcPYzFrbkccel4J5uNrmvBQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB6272 On Tue Jun 2, 2026 at 8:42 PM JST, Eliot Courtney wrote: > On Tue Jun 2, 2026 at 12:21 PM JST, John Hubbard wrote: >> Add external memory (EMEM) read/write operations to the GPU's FSP falcon >> engine. These operations use Falcon PIO (Programmed I/O) to communicate >> with the FSP through indirect memory access. >> >> Signed-off-by: John Hubbard >> --- > > >> +impl Falcon { >> + /// Writes `data` to FSP external memory at byte `offset`. >> + /// >> + /// `data` is interpreted as little-endian 32-bit words. Returns `E= INVAL` >> + /// if `offset` or the `data` length is not 4-byte aligned. >> + #[expect(dead_code)] >> + fn write_emem(&mut self, bar: &Bar0, offset: u32, data: &[u8]) -> R= esult { >> + if offset % 4 !=3D 0 || data.len() % 4 !=3D 0 { >> + return Err(EINVAL); >> + } >> + >> + let mut emem =3D Emem::new(bar); >> + emem.begin_write(offset as usize)?; >> + for chunk in data.chunks_exact(4) { >> + emem.write_next(u32::from_le_bytes([chunk[0], chunk[1], chu= nk[2], chunk[3]])); >> + } >> + >> + Ok(()) >> + } >> + >> + /// Reads FSP external memory at byte `offset` into `data`. >> + /// >> + /// `data` is stored as little-endian 32-bit words. Returns `EINVAL= ` if >> + /// `offset` or the `data` length is not 4-byte aligned. >> + #[expect(dead_code)] >> + fn read_emem(&mut self, bar: &Bar0, offset: u32, data: &mut [u8]) -= > Result { >> + if offset % 4 !=3D 0 || data.len() % 4 !=3D 0 { >> + return Err(EINVAL); >> + } >> + >> + let mut emem =3D Emem::new(bar); >> + emem.begin_read(offset as usize)?; >> + for chunk in data.chunks_exact_mut(4) { >> + chunk.copy_from_slice(&emem.read_next().to_le_bytes()); >> + } >> + >> + Ok(()) >> + } >> +} > > Both `write_emem` and `read_emem` are only ever called with `offset` as > zero. I checked openrm, and it looks like there aren't ever writes or > reads that don't start at zero. So we could simplify the code by > removing `offset` and starting from zero if we will never use a non-zero > offset (given we have auto-increment). This also lets us remove > `EMEM_MAX_SIZE` and some `Result`s. IIUC the way FSP communication works is that EMEM is (in theory) divided into 8 channels. Only one message or reply is ever processed at a given time (i.e. this is not a ring buffer), so the only values valid for `offset` are that start address of each channels. So while we might need to have some sort of pseudo-offset in the future, a freeform one is definitely not adequate for EMEM and for the time being we are only working with channel 0 anyway. Thus I agree that it makes sense to remove it altogether for now.