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Thu, 23 Sep 2021 06:17:41 +0000 Subject: Re: [RFC PATCH 2/4] DRM: Add support of AI Processor Unit (APU) To: Dave Airlie , Alexandre Bailon Cc: Dave Airlie , Daniel Vetter , Rob Herring , Matthias Brugger , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , ohad@wizery.com, bjorn.andersson@linaro.org, Mathieu Poirier , Sumit Semwal , dri-devel , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-arm-kernel , "moderated list:ARM/Mediatek SoC support" , LKML , linux-remoteproc@vger.kernel.org, Linux Media Mailing List , "moderated list:DMA BUFFER SHARING FRAMEWORK" , khilman@baylibre.com, gpain@baylibre.com References: <20210917125945.620097-1-abailon@baylibre.com> <20210917125945.620097-3-abailon@baylibre.com> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: Date: Thu, 23 Sep 2021 08:17:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-ClientProxiedBy: AM0PR05CA0090.eurprd05.prod.outlook.com (2603:10a6:208:136::30) To MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) MIME-Version: 1.0 Received: from [192.168.178.21] (91.14.161.181) by AM0PR05CA0090.eurprd05.prod.outlook.com (2603:10a6:208:136::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4544.13 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?bFJEQVNzM2ZMazNJQlFkSTU5QUFDTjNVakNRM2JJR3krMWxzVEFIUWRQM0J2?= =?utf-8?B?eVlPNTM1Q004TklzUXp4T2h5TldydXdGZWxhZDFXeC80L2NSTWFFSFhINTNz?= =?utf-8?B?RFBQa2JaRnFUbVZGYTJmbVNpVnlhWUs0bUVBbUZNN3VnQXFuRTFoUWwxUlBi?= =?utf-8?B?YitGdjVZVUFnMzE3VGVwRUpqN1FSZ1Y5QmFFaEZobi9CZjBpc0VkSlJNajZ4?= =?utf-8?B?SkNSVVVnTlRtbXJpaHFOQ1FSWjdlbE9EVjVGMWl5K0xyTTRWZ3pQdktmZjc1?= =?utf-8?B?Qm9wZ2xLcGl2RmdWOE9OaVMra09samlRVnRyRGlaK2RkMHB4aGJkdnRtek1E?= =?utf-8?B?M2g0TFF6UlBLQU0xZGtIaFRKNnNnaTBOY0wwam9LZFI1RU9hZFdLMFVlZHlo?= =?utf-8?B?OEdlc2pTdDJjVFRRMHJqUlBJV3MrMHhIQlpFOElMVWNUemRveFlJWEtZNmsv?= =?utf-8?B?TkRSdjJjVElYdEJSK0F5OW5DaDd0MWJ4cWZkQnhLM29HU1JJeFRRVFVkdFJW?= =?utf-8?B?akpuZWluSWRxK0NuSzN5VmgzeTIvTXpLZ2E5cTRTb1FOUDdkSWFudkNkSExM?= =?utf-8?B?Y2ZnMlRSUGRTcVIxR3JxR2Z0NzdHZWg1ZFlpR3NhU0psOFFSVUZwdVAveEdV?= =?utf-8?B?REJKeVlrNFBqOUdZSFZXRDRSQWFob3ZCampaakVpbUZ6OW9xY21UK0xQckFa?= =?utf-8?B?N05tb2UrUCtJbjZwYVFScHRZVHcyTC9sVjlydFdMaUlmRzZjamhFalZST09q?= =?utf-8?B?TkZFSXRaeUp3dHlLYlZjOUx3ajZFQWI5a21HVVlhZGQ5dE9QaDhhV1hCNUFD?= =?utf-8?B?VkhOV3hMRFdISlJJR2czSmVZeE5KaHg4Z0JqZ0JxZGlxMzdWSlVmS1MvbThy?= =?utf-8?B?bk9kb3oxTk1oMi8zL1hKZVpQNUlCY1F1WVptdmlZVUhmWXVFVFg5dnZiMUFG?= =?utf-8?B?TWZQRysrbVhOblF3bStrM0ZPNjBnS1pBOVAvRmsvSitad2t6QWFPTW9lc3Ba?= =?utf-8?B?L0pKTDkxZ2FjWjZTd1g4TUw2dnY1elVEU0pVdTJDckYyZmxBZEo2QW1aNDdV?= =?utf-8?B?ZG1XQ3F6SnoxNlg5Y09QUWluUEw4bHpWZXYyV2kvU1NnYUdkYnd6MDdmd0Q0?= =?utf-8?B?eUxpclJ4QXVXdHpRUXo1cXU2Sno4NDRDL2tRS1pGTCtxdWhtd3lTbEFreVJ1?= =?utf-8?B?UzZRbjY5RTB0RWIyaEZSSkpCL1NpR0pEdzJCME1EVHFZK2U1NDgxaW41MDBr?= =?utf-8?B?VHBqdzFHQjhQb2ZMaFdWQmwvU2dSTkdBYTZna3NWaTZrckFjZ1diRHpZYXJW?= =?utf-8?B?M3h4NTI0T1JGSGE2eG11WGtKSlpYMm1pamZjUGs3Tzg1aDZjNUNNWW55RCsr?= =?utf-8?B?d210bHZZOE92b2tJbThLSzU3THVzS09WTUlYQW91dkNjcjFEaFN4bUdPQVBV?= =?utf-8?B?UytlRi9YNld1VlBXcnpHZm16eHc0Qjk3RzNibHR5ajI4bStwWElOSjB5Q0Fh?= =?utf-8?B?YXFRTUxjTGUvNm9kalFwajRLL1phbmZzMVVPNHFsY0ZrYjZxcEhsRFdwQmkx?= =?utf-8?B?OFJKSFc5MEZxVVhucEd1WlVBbkp1OU1CYy9uejhDY003Ymp5WTdyaE9zemtv?= =?utf-8?B?N056UlNRZlZHRnNJcnh1a1d0WElGYjlSeEQ3djBOZE1vV1dETjQ3OG5aYnA0?= =?utf-8?B?azhHSkdhSENJZ2ppTnRNSFdCeDRGckh2SUg3VkY2K1VESkZkbGIrOGdHS2Qv?= =?utf-8?Q?yQauzGVL4ggD98lZmViwOwXn9R9TDtFxNgTsI/F?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5a93b627-b420-487d-f228-08d97e59d945 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3775.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Sep 2021 06:17:41.3773 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: i8ka79Yy4qjAzt5uimpZkB9KaQQt1SH7Mxl/Xj6gWKZyAoXfTP89tFfbNfWG3lyg X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4375 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 23.09.21 um 02:58 schrieb Dave Airlie: > On Sat, 18 Sept 2021 at 07:57, Alexandre Bailon wrote: >> Some Mediatek SoC provides hardware accelerator for AI / ML. >> This driver provides the infrastructure to manage memory >> shared between host CPU and the accelerator, and to submit >> jobs to the accelerator. >> The APU itself is managed by remoteproc so this drivers >> relies on remoteproc to found the APU and get some important data >> from it. But, the driver is quite generic and it should possible >> to manage accelerator using another ways. >> This driver doesn't manage itself the data transmitions. >> It must be registered by another driver implementing the transmitions. >> >> Signed-off-by: Alexandre Bailon >> [SNIP] >> Please refer to >> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2FDocumentation%2Fioctl%2Fbotching-up-ioctls.rst&data=04%7C01%7Cchristian.koenig%40amd.com%7C53a0ef2630404ddc4d9408d97e2d409c%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637679555123878415%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=6oVXAAOjQX%2FnDzJxZIAALqjDourHdrdGF6QVQKR58KI%3D&reserved=0 >> >> here and below in many places. >> >> There's a lot of missing padding/alignment here. There is also the pahole utility which show you nicely where you need padding for your IOCTL structures. For example "pahole drivers/gpu/drm/amd/amdgpu/amdgpu.ko -C drm_amdgpu_gem_va" gives you: struct drm_amdgpu_gem_va {     __u32                      handle;               /*     0     4 */     __u32                      _pad;                 /*     4     4 */     __u32                      operation;            /*     8     4 */     __u32                      flags;                /*    12     4 */     __u64                      va_address;           /*    16     8 */     __u64                      offset_in_bo;         /*    24     8 */     __u64                      map_size;             /*    32     8 */     /* size: 40, cachelines: 1, members: 7 */     /* last cacheline: 40 bytes */ }; And as you can see we have added the _pad field to our IOCTL parameter structure to properly align the 64bit members. Regards, Christian. >> >> I'm trying to find the time to review this stack in full, any writeups >> on how this is used from userspace would be useful (not just the code >> repo, but some sort of how do I get at it) it reads as kinda generic >> (calling it apu), but then has some specifics around device binding. >> >> Dave.