From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=pass header.oldest-pass=0 smtp.remote-ip=52.101.61.49 ARC-Seal: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=pass; t=1794752613; b=CK97hY0uYwgKccVjR5XS1+nyk42SGn460ENBsbN0e1FenpkyJJIDUGw31Vsu8qv5eBio whRJx66q8QVtjmM8N0LoKQXfA7KNxNHxldc86RAzlQLnpjhHr0RMhvLxYaSYt07XSneMN es8pVDJXVDeWcPg+Jo03aPMRDTN0vMrQXgTxCJS+RZpBu/cTfkHemelMZdSfVMU35HRWl H0YIuuwYnUJEoFi5s+SqQQdDf78MflMxl/vkklgYN+cubNYpmQV4FMOoRDujqPpGNL0Ov CiV80gqc6J+vJfKaL/MxvR2WMBChxXFYtBLhz8+aXb/ExfgtZ+pXHBqHIJM7D6WT8pQ== ARC-Message-Signature: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794752613; h=DMARC-Filter:DKIM-Signature:Received:Received:Message-ID:Date: User-Agent:Subject:Content-Language:From:To:Cc:References:In-Reply-To: Content-Type:Content-Transfer-Encoding:X-ClientProxiedBy:MIME-Version: X-MS-PublicTrafficType:X-MS-TrafficTypeDiagnostic: X-MS-Office365-Filtering-Correlation-Id:X-MS-Exchange-SenderADCheck: X-MS-Exchange-AntiSpam-Relay:X-Microsoft-Antispam: X-Microsoft-Antispam-Message-Info:X-Forefront-Antispam-Report: X-MS-Exchange-AntiSpam-MessageData-ChunkCount: X-MS-Exchange-AntiSpam-MessageData-0:X-OriginatorOrg: X-MS-Exchange-CrossTenant-Network-Message-Id: X-MS-Exchange-CrossTenant-AuthSource:X-MS-Exchange-CrossTenant-AuthAs: X-MS-Exchange-CrossTenant-OriginalArrivalTime: X-MS-Exchange-CrossTenant-FromEntityHeader: X-MS-Exchange-CrossTenant-Id:X-MS-Exchange-CrossTenant-MailboxType: X-MS-Exchange-CrossTenant-UserPrincipalName: X-MS-Exchange-Transport-CrossTenantHeadersStamped; bh=RQHnQzoMs5gWVgh6i51Y33kxUD4/Ln7a4zKCXrFODW4=; b=g5kQH5rD94mNVdDlYezjcGWrc7me4JCiawreL4n6l2cae/hob7k572YMc29qf/wxpOby 4vX6QvSSIOoI8a6ddBVUYonFVwIPovX/3Y3DH+aO1uzIwJNjfB7QdoFoMrW8exPF85OF3 KUXUYRmLm1ggnA6KbUA8H3Kuw9nlg/FHUrXAgAVrSuEJnVL0ebtbHRq/OtP7rpNLyVaJQ 1ThSjUJObKfSIcfp61TP9XKF4WQuQxM+BTKpmjPOkEYvbKLs2db3Jerw4R2q4I2vegXYV wBynisFHXyI7fjrFQeG2DSSZMI9Ond90xqiNnkAfdSGyxs97jQVo0thKs7fJN+F7aHg== ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass header.d=amd.com header.i=@amd.com header.a=rsa-sha256 header.s=selector1 header.b=33omDWR7; arc=pass header.oldest-pass=0 smtp.remote-ip=52.101.61.49 Received: from DM1PR04CU001.outbound.protection.outlook.com (mail-centralusazon11010049.outbound.protection.outlook.com [52.101.61.49]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (secp384r1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 848F4606A31E; Sun, 15 Nov 2026 14:23:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 848F4606A31E Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=amd.com header.i=@amd.com header.a=rsa-sha256 header.s=selector1 header.b=33omDWR7 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=CM4fBVbHL1jpy4E6qmfqy6PwsZWxN8Uo12NA0xaDWPkgFt/ARXX8wThEQ5WNsCjmDd5+uRzErD8pg35axWmB+cYvWdHPhPkntA7a54Ymx9Qo8Z3BE78BHdRX0XOS/CSfVmBM3f9/pru7bdUwBVLF11uRoVeAE1F/TAz9kPXjulMTWh1QmY+DkvQ/rGsdqFSgDaA60XpNnu8XZtscKNczYEBIQSiZgJVodfMDmw2M9FXlaUVFAXwCrGmIvmqyImnl9pXO7vMhH66LKD0pJDiCJ+awPQeXsORO0Ak94WevsJKMUK+muOv5f5RTty5wyPufrEYsZBpjizNtwidtcxBpuQ== 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=RQHnQzoMs5gWVgh6i51Y33kxUD4/Ln7a4zKCXrFODW4=; b=pe3toHZGRYH0DEXqhaVlpVG2je1JZKHVY4qFPCxm4oJxSFUFTffxWycp3e6CSN2FDz6uqx7cEyMulK2eMYCPPXkWIXy5PUDTBVh1wvtfXO3EVR+pA6oASUbzAKxOYIHNtafU81EjvbMiPVsFwULBKFzgVGaj0RwUyNzLo2tZ5rQYrZpZFtMqH5kjUJTmnPWmlxOC3e9hKLYBAWz4CLHv11JIImuLjFJWmCAsqyOPFlLpb8c/NV4uYdyS7c0TQC7EqN6I3FgqQrBxVBJHqqmmYWYKruJ2ONXnBTCtKO6eZZLaBq5AbazVTPNT10dM4RUNmApttIjXSbc7Gmafz9LK9A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=RQHnQzoMs5gWVgh6i51Y33kxUD4/Ln7a4zKCXrFODW4=; b=33omDWR7t7xaz5BHlEqF67KQLRh/SXHlp+NpgyrW1y3//JV+uyXt5+/OOOAdWe/YN389o09S50E/Qt5NGVGDnflwCI9/bM1+B7B9/gOrTmDGirrzP7j4K7A7YfCfj7xN96/nhDjGVaOL+M+tqZc73+MOs/RENK3Jk6x+Dr9IDxs= Authentication-Results: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from PH7PR12MB9174.namprd12.prod.outlook.com (2603:10b6:510:2ed::9) by DS7PR12MB5912.namprd12.prod.outlook.com (2603:10b6:8:7d::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.615.10; Sun, 15 Nov 2026 14:22:22 +0000 Received: from PH7PR12MB9174.namprd12.prod.outlook.com ([fe80::eaaa:b430:ba9:5dc]) by PH7PR12MB9174.namprd12.prod.outlook.com ([fe80::eaaa:b430:ba9:5dc%7]) with mapi id 15.21.0615.012; Sun, 15 Nov 2026 14:22:22 +0000 Message-ID: <804443a9-b50c-4d22-bded-8c3d908ace08@amd.com> Date: Sun, 15 Nov 2026 08:22:20 -0600 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] platform/x86/amd: hfi: Stand down when amd-pstate CAS is active Content-Language: en-US From: Mario Limonciello To: Vishal Badole , ray.huang@amd.com, rafael@kernel.org, viresh.kumar@linaro.org, perry.yuan@amd.com, kprateek.nayak@amd.com, hansg@kernel.org, ilpo.jarvinen@linux.intel.com, platform-driver-x86@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Krishnamoorthi M References: <20261114150310.1377654-1-Vishal.Badole@amd.com> <20261114150310.1377654-3-Vishal.Badole@amd.com> <404553c5-60b3-464a-8d76-7850120f3d58@amd.com> In-Reply-To: <404553c5-60b3-464a-8d76-7850120f3d58@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SA1P222CA0131.NAMP222.PROD.OUTLOOK.COM (2603:10b6:806:3c2::12) To PH7PR12MB9174.namprd12.prod.outlook.com (2603:10b6:510:2ed::9) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH7PR12MB9174:EE_|DS7PR12MB5912:EE_ X-MS-Office365-Filtering-Correlation-Id: e0be5b97-9e03-46ad-f5b8-08df4323dd3c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|376014|1800799024|366016|921020|10067099003|11063799006|4143699003|56012099006|261021121427099003|261028144727099003|261026121527099003|261022105027099003|261022075727099003|261026140227099003|261102123227099003|261009223027099003|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: SC0sofwDVmujYevTtKLas23WfWahcSsJ/Rry9rUMxt/XaGplWI203aRBab2dZ9Dm0sKLotffogF/NY3Kt5GRSHl6hcgdYBF45k+3rDZbbrhmg8BJRzTVUDx/F9RcyB/KC4uxg4ckVJxpNDxytawz4cl0m8/efzUTTZO5avGeVdl0k9XmjmHQST6kDP3npmzjcEjPb97MFSBttfe5czJ9hArfE1oT2rabdOQlNRVweMQ7Tgcct4MFJonOUl24vEvqaPykUC0cw5NeqL6VrB2WUoZmaAnfZxmjcfN9jcV2035o4ccqtWUpgIsaeL2yv2U1sYR7Fw+d3odDtjhINvTqMPtUhA4dmgN8T+jwuu5ZAbnV3nn3B9+rR0ilHu+DMUVPC4WU1eJP1YQ48j7TeC4MVc/ZQ7FbTXHqPazclO/rVRFRse04koFex4qbZmViESGNnsHD6dZ4uPuRoqbdRDKgGmmvcyfNyjiyEN3P56JQm1X4EPTUlW/HDiS4aSst9sWxQBzaL16q6c8DutBJodcYIJgu+jMLDWmmOeHmCLmRDFAv+svPnRPjKvmSvEoaNF9+amxlmoRatidgE/4VS8Lx5TC6GCg9GgcjoidzhkSHUi9QVzSPEjjT6azCh+zdQ88XOesoXWYhw/DJz+Ue5O35XYss6rQj57bhRBnfgg90QpOj20gCHKcj/io9I0D0oR5Zbhd+oglav4keBRC71BsjFg== X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH7PR12MB9174.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(376014)(1800799024)(366016)(921020)(10067099003)(11063799006)(4143699003)(56012099006)(261021121427099003)(261028144727099003)(261026121527099003)(261022105027099003)(261022075727099003)(261026140227099003)(261102123227099003)(261009223027099003)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?a0J1R3BNRWlsWHBZWnZsK2VTUGJiWEdyemRmZXg4UUxDN01ucjZ2aW5JbTFB?= =?utf-8?B?anJMYzhudFJQU1JpTVQ1cEF1dkxwWktSU1YwakdmQU1tdE5qMm45WW1FbjBJ?= =?utf-8?B?Tk5YR0ZxRm1Da3MycGx0T0N5eGNMZUk4VC94V2xnUG5nc2RGSU1sa0lQWWsv?= =?utf-8?B?ZDhob0FJeWgrZlU4K2ZoSkhZNlpEeFYveEtnOWNMTVlaRytnSHV5RjFFS1RJ?= =?utf-8?B?a2NFcW8zdFNIbTdpb3JIaHUvZTcrVWZ3aTg5dXV1WGxzK1Y4SmZxZkpSQzNY?= =?utf-8?B?L1pEV2RrOXVuZkFWYmZvQjNqWWZkTExSd1RiUzNsQ3UyT0ZxVDV3ZGhhQlJC?= =?utf-8?B?RithSkFxZ0kvbFV4S2RKS1BTNWVvaGJiSkhScndpL0hNWTFWenBvZEhBMkQr?= =?utf-8?B?S1I4djFLdkg0eDVpTmVvYjFpc2NmaHNGSkQrSktOa2ttTXpUem05dzFHNnJL?= =?utf-8?B?T1haWG44M3UwaHlvNUwycVNaK0xGRm56MDN4L1JXaTNIblppSFRERThiVmdx?= =?utf-8?B?VDg3NWlMamFyQU9uYXZZNm1HYUp2ekwzY0dvSDlHK0h6cXljRllhMmhYTVhs?= =?utf-8?B?K255L1N0ZVdrVXdGek1QYTQwaFRzWmVmVktWQitMa1J1ZmtTam9IdjAyVjV2?= =?utf-8?B?bnFyblBLTG1ZOU14OWxHaVdKam9QWDVuaHFVUGZtNEVQaEg1UkRMZkhvSVls?= =?utf-8?B?WFY1ekRXRzhzcEZyd0REQlAxRXgzMW13bXZJMWhydG5xMUMyUnZwcXBzalpr?= =?utf-8?B?bDlVT3BFckt1aUM4alJWNmR5K2ZacW9IYW5zd3dVV1ZQdG41ZVd2cXpmS1No?= =?utf-8?B?SWhDRW1NbmR1UWl2MHV1VDBYVXc0Q1MrcC91WXZ6dHg1R202NWZjRnN2Mmw1?= =?utf-8?B?RjViWFJqcFZLNDhSRlVDcWx5NWdFdU8zRzdneG1QTFRpRHVJQTBKd21DNk80?= =?utf-8?B?VjdWbElaL05jYXpONG5OUkVqNVljSU85NUp4ek5BVUJFTndZQzJJVTRTeC8w?= =?utf-8?B?Q0RkSW14Q2loNlptZExOYUI5SmRxdUx4VEVPaW00V0U4VGxkOXZHcDBldCto?= =?utf-8?B?Tkp0SkorV01ITWxYNTE5WjgyRURUcTBjS0JpMmVnaEl1VmdHQUVxV2VKK2VD?= =?utf-8?B?azA5OW1sd2RNSmdBc0FKQXl0YVB4cjNkTGpmcnNCSE9YWU9OSkh4Vkpldmpm?= =?utf-8?B?VHRmaUtyWGxLUysyY1RuRmVHT0pTTW8zMVdlbUpGZzh5MytOdGZjMXVzKzA2?= =?utf-8?B?ZEx5aUVWalZUZFV1OCswZGQyWGRjQU5rZkQrdDN3THkrZWc4OHUzUDBUTW5u?= =?utf-8?B?M0trczZOcm0rNFpNZlRqbTNRMXFwaTUwc29hWWM0NVRGTU5TRzVoOW5XaDky?= =?utf-8?B?K2xJOWoxREtoZ2d4ZWpnRUtQalBKSTdpT29lb1ViV0RKbTY0YktXd0FuaU1J?= =?utf-8?B?TlNiOTN6QkJlSnZpTGR6OE4wODREUkJuZDcvK2lFUFJhUlovQjl2YnVLNlZD?= =?utf-8?B?bzRFOW5SbDV4bWdxVUNvV0xrQXFKdlNpUTJ6NWxVL0JCb2VjVkZyVlpiREVB?= =?utf-8?B?aVllSDF6L2NjWEpCRWFsc3BuWjE2N05DUnR5RGU5b0JaWUNWcUYxOS9XYy9r?= =?utf-8?B?cXJWQ2g4Ri9INjFJUVJEZjhVK09aMDZjT1orMWJxa0R4ZGlnTXE3R0UxMGND?= =?utf-8?B?ZjNpS2lXYTVYZ1ZCTEx6bFBtQ2FrQk9QUEF2QTJ1Q1YybjcrOC91eWNFZXBi?= =?utf-8?B?K0tQRHBDRkhWcE0yUEx5MnJtQ21kS3MrWWFFZUlFMWJmL2dLNm12QkViVEdR?= =?utf-8?B?SUh6azNWdHdtWWZRR240K2FkWDFIVGR6eHkxRkdiQ3lUcnRmQ013TXhRZ0RV?= =?utf-8?B?eUdBM1BVVEJkTit5dVoySjFZMjQ0aTN2aTE1ZHdNZ1JETXMrT2xmN2hVKzFy?= =?utf-8?B?bnordGxYL1VacDR4ZWZIUEZZN29pSnhOK3paVjJteDJ6N2M4RHVFUDZqa29U?= =?utf-8?B?eUNTS1hpZy93bExlQ1R6M2N0WlVBWnVjRmhNUFd5YXdnWi9GcHAzdFFFbVJj?= =?utf-8?B?eUdYMkF6bzZiU2J4aHl3bVA5aFVCaFQ0WnNPS2hoN3IrTzZYUHk1TXIwODda?= =?utf-8?B?Vm5DUFJWYjF1V1VzNmNjRENBRmdXWWR5b0VVY0VtVzdqNnRjMy9RQkR6V3hH?= =?utf-8?B?b2ZXYW1YNFg3NDVDR2NDYVErK1pHWVVoSGpOUG5HWG1GK3hoQStNSTZBMHBL?= =?utf-8?B?SGlOUVBoTWRSWFVqYWJkTU53MlM2NkxiemFTemZXajhyUjFmZ21rOVg3djBJ?= =?utf-8?B?T1RDSndjV0d3SStCSjg0Y3llaTgrRmMrRE56M0V6T1NnZGRKNWo1Zz09?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: e0be5b97-9e03-46ad-f5b8-08df4323dd3c X-MS-Exchange-CrossTenant-AuthSource: PH7PR12MB9174.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Nov 2026 14:22:22.5801 (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: EiXkMbmt3/nb2qObe3R/YgRSKrVjoNoMytDcEomwCDCKHhDQ4ozkXWR8cGozaJERSxMWgJiS9sifTo9u8MjVQQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB5912 On 11/15/26 08:16, Mario Limonciello wrote: > > > On 11/14/26 09:03, Vishal Badole wrote: >> From: Krishnamoorthi M >> >> When amd-pstate CAS is active, it takes ownership of per-CPU capacity >> values that the scheduler uses to distinguish performance and efficiency >> cores. amd-hfi manages the same scheduler state through its ranking >> mechanism. Running both simultaneously would cause them to overwrite >> each other's settings, leading to unpredictable task placement on hybrid >> platforms. >> >> Avoid loading amd-hfi if CAS is enabled. >> >> Signed-off-by: Krishnamoorthi M > > When a patch is authored by another person and you send it on their > behalf you need to add your own S-o-b as well. > > Think of it like a chain of custody. > >> --- >>   drivers/platform/x86/amd/hfi/hfi.c | 8 ++++++++ >>   1 file changed, 8 insertions(+) >> >> diff --git a/drivers/platform/x86/amd/hfi/hfi.c b/drivers/platform/ >> x86/amd/hfi/hfi.c >> index 86a7f4332c35..b6878614e2bc 100644 >> --- a/drivers/platform/x86/amd/hfi/hfi.c >> +++ b/drivers/platform/x86/amd/hfi/hfi.c >> @@ -29,6 +29,8 @@ >>   #include >> +#include >> + >>   #include >>   #include >> @@ -536,6 +538,12 @@ static int __init amd_hfi_init(void) >>           !cpu_feature_enabled(X86_FEATURE_AMD_WORKLOAD_CLASS)) >>           return -ENODEV; >> +    /* amd-pstate CAS owns heterogeneous core scheduling when >> enabled. */ >> +    if (amd_pstate_cas_active()) { >> +        pr_debug("amd-pstate CAS is active, not loading amd-hfi\n"); >> +        return -ENODEV; >> +    } >> + The load order happens to work; but AFAICT this is just by coincidence (link order). If the link order was changed in the future this could break completely non-obviously. I think it would be most ideal to add deferred probing support or forcing HFI into a later init call phase. >>       ret = platform_driver_register(&amd_hfi_driver); >>       if (ret) >>           pr_err("failed to register HFI driver\n"); >