From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=os.amperecomputing.com header.i=@os.amperecomputing.com header.b="LSsjtRFi" Received: from NAM10-MW2-obe.outbound.protection.outlook.com (mail-mw2nam10on2100.outbound.protection.outlook.com [40.107.94.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFD779A; Thu, 30 Nov 2023 00:39:59 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=mkouRmxDG7nDv6VJZM5IP3OhX9EgBSHEnjxIjH15ng6JxRsdsiLxgX5qVvhSiX7nGQchd9i7bB4qyzsXoc5RmtAccT0O/O1ArCgFlb+88pa4bk5dMuDylVfg/9xLy07xQE+7iVwp1k36IHbO3HV454bYmNt61C9ufSXtggWTDhkfl/mvSM/Mwe4Xkrpf/Lk4/NjiJWPU9M42dNRkA4rMKCx8tcvwaHPBOdDFOj10tN9eYxBlT8ZSCyCsAwoebXjTAktmdgq0ivsK2sGJwX/7e+Q1JHsOdxiDCYK03Ok7UXIOuLVU/Crc93K1C/Ht4x+vLg8R0RX2ZIRu5BT5kyIHow== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=yV/F29IfBt/gtR2BrPHsqcXTL1lajfnG9dJh+c70JEY=; b=BmbmFvA4WUAleonWLrv9ZDM0mhvx3texp3AgvyjYdaIqbEkffnRMDSizlryB6uxft+Gzgs3NjPlwN3l1ud7AtCCBaXznOB/14OL5k0v4dwJL3R3F7jX+sY+5SPWlivRTl2aY7uiAdXQHK1//jRoLsl8ZNKaoXAvXUfmKFdzg60bpN5uep9H4Is1MWm+gpoV067txItxq1W66uGyAD5tL+BwbHn3ZnbX620DjD1D3KAzPoZ+skR9yepCVLxZUN5hP8SfpoU1gt/Ex2RQkpQwBZikMsbFmuu1JqaX4bqmiaUcWaPZoImBSiSP8s1ThOaIshU5wXpsm27Ies3hALzR6Zw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=os.amperecomputing.com; dmarc=pass action=none header.from=os.amperecomputing.com; dkim=pass header.d=os.amperecomputing.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=os.amperecomputing.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=yV/F29IfBt/gtR2BrPHsqcXTL1lajfnG9dJh+c70JEY=; b=LSsjtRFin/HjufzxrKUA4bOEhzQ8qa5r89fiIHUkb82DiozA6kTPej+0gatnr7zI0ZPfMG49cVascfp4GHHshegEvBO/9cbBFRHStx5DlOqNABSNAaqZcnD8yZ7IWQMns2LRrX5iG1ESrUFgAn8nxXQD0bSqdfxc29ZHVm0Qrho= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=os.amperecomputing.com; Received: from SN4PR01MB7455.prod.exchangelabs.com (2603:10b6:806:202::11) by SA1PR01MB6560.prod.exchangelabs.com (2603:10b6:806:1aa::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7046.24; Thu, 30 Nov 2023 08:39:56 +0000 Received: from SN4PR01MB7455.prod.exchangelabs.com ([fe80::5682:1d84:171a:1d68]) by SN4PR01MB7455.prod.exchangelabs.com ([fe80::5682:1d84:171a:1d68%3]) with mapi id 15.20.7025.022; Thu, 30 Nov 2023 08:39:56 +0000 Message-ID: <706506b7-a89c-4dfc-b233-be7822eb056e@os.amperecomputing.com> Date: Thu, 30 Nov 2023 15:39:45 +0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mctp i2c: Requeue the packet when arbitration is lost Content-Language: en-CA To: Jeremy Kerr , Matt Johnston , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, openbmc@lists.ozlabs.org, Open Source Submission Cc: Phong Vo , Thang Nguyen , Dung Cao References: <20231130075247.3078931-1-quan@os.amperecomputing.com> <473048522551f1cae5273eb4cd31b732d6e33e53.camel@codeconstruct.com.au> From: Quan Nguyen In-Reply-To: <473048522551f1cae5273eb4cd31b732d6e33e53.camel@codeconstruct.com.au> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SG2P153CA0018.APCP153.PROD.OUTLOOK.COM (2603:1096::28) To SN4PR01MB7455.prod.exchangelabs.com (2603:10b6:806:202::11) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN4PR01MB7455:EE_|SA1PR01MB6560:EE_ X-MS-Office365-Filtering-Correlation-Id: 1ba9933a-9f55-4a36-d22b-08dbf17fee39 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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:SN4PR01MB7455.prod.exchangelabs.com;PTR:;CAT:NONE;SFS:(13230031)(376002)(366004)(136003)(396003)(39850400004)(346002)(230922051799003)(451199024)(1800799012)(64100799003)(186009)(5660300002)(2906002)(6506007)(6666004)(966005)(6486002)(478600001)(4326008)(8676002)(8936002)(86362001)(31696002)(316002)(54906003)(110136005)(66476007)(66556008)(66946007)(26005)(107886003)(921008)(31686004)(83380400001)(2616005)(6512007)(202311291699003)(53546011)(38100700002)(41300700001)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?clArZ2hvOUlmNXl4bEhVYkk3RjhweDVYWHZzMnNzYi92UGROb2c3R2hTNFlN?= =?utf-8?B?L1VieWtFMDNtWk9WZm1sT3M3OGo5U1BNK2hoOUhueUNUSE8za1hZWXhVZ08z?= =?utf-8?B?S1ZSUDdpV1hyc0w1ZFUwNDhoamhhTkZweDJWcjIyemJ1NE9hZ0ZJVnFUOThv?= =?utf-8?B?Zk9LY2NMS1d6ZnVMaEtFU0x3WW9TRUIrMDRrVWFxOXR4U3AxeXpNUWRPY2NW?= =?utf-8?B?RTVsdGNmMHllbVYyVWFUWFRQSWhtRXpWNkErYzJrQ0FnZVBBSXV0Q1ZZTXRK?= =?utf-8?B?M1hCMnBQcythS0ZpN2hMU0VtRDJoN2dRcmJzT3lNZ1J0VDM4NjBjTWowUEtY?= =?utf-8?B?Mkh4MC9WdlIxMnN4YlVUUW41YmY5bkxQekdpbExEbGdhMFJkUFA3cFVSMjAx?= =?utf-8?B?OFZTS2dtRm5LWThQeUFtNWRGaTdoZGpDaExZQmczS2M1YXE0R3lXTlFPcWZN?= =?utf-8?B?VGFkN0puMlVOQlZ5T1RqaDNmTzR6OGh3WVFjMTRSQnBvZ2dtNFRkRXRDMDlG?= =?utf-8?B?QVR1dEZSc0dtYktMSThBYnFxeGRRQXFCTnRVT0U0V2JqMjlLcmNGb1pCTGJs?= =?utf-8?B?Tlc3ZFpHUGFpWmhlSTJDdXhHeHdNZ2w4SGp6S0hMTE1zYUs1TWlZeGVxcDA0?= =?utf-8?B?Yk9Jb2lORTBLME81dDl4MmFLcnYxVXRSbGFPSkxEQ2U2OGpKZTkvSVJKQ1I5?= =?utf-8?B?eVBWdmNvaGRic1B6alF3NFV4bmR6QXNJVklROGZZc0J1RS9JcXVadjFicUlp?= =?utf-8?B?WXBOUm5NbEhraHNRUmFiNVJENVF6NjFyY2YvMFUzcnJIaWduWDdqTkpsbDZa?= =?utf-8?B?WWEvd1VNaytPL3VSU3ZCN2N2UnpqNnNQWDNKVlNYak5hc25TeGJhTnViZEhG?= =?utf-8?B?dVZya0tDSVhwcFFDTDJmN2RrQ056dm1vY3F5cUx2c0dHQ201d3Y5Q092YUUx?= =?utf-8?B?NjFobDFwWCsxa0lOVWtSem5Eekt0Qk1GdXJxMTNDSzhkekJZZk94dE1GNlVR?= =?utf-8?B?ZVJld1dTYWJMN0trNnd0bGJZOXFOSnZrOE1OSnNiZUlkdjlrNGJocUhkdXBt?= =?utf-8?B?VFdOdDhJSVpMeG43clVyRFc2Qi9zMmJCcWRhUE4wRHJ3c1ppYktCblpna2dz?= =?utf-8?B?L0M5OE5BbWtXbmhmbHlpT3VHbFF4cThpdzU2MWVidVl3NE9CRU1RNWRtM0lp?= =?utf-8?B?NnN5M3BTcU5kb3U2aTRKa0drdjdERW9xTVFTdE1valordUZvaU1JKzA5aFpt?= =?utf-8?B?aGdWZFo5UXJMTlk3Tkp5LzdMY1RuVFgwbEhVOGpTMTYyM0NwRW1xRG5jeDdp?= =?utf-8?B?Y2VVeXdsR0pQdkg4UkI0MjNVSFZnNGtueC9DMUNLZFZNT1dycXdDZlNOenZT?= =?utf-8?B?dlVjMVE3SUw1REI0UXVCMVAyTHRIaERTOW9aVC94SUhyMVk1b1MrazNSRUlV?= =?utf-8?B?bTFHbE5ibCtqd3QrenIrUytBQ243dE9MWGhpZjNlY2tOT0JmS1hXdWVDTEFq?= =?utf-8?B?dFNxRGxsU2hmbE1BTko2Qzl5S2tPSjZtMkZzbFVkem5EM1Fhd3BoTUVzV1Nq?= =?utf-8?B?UU93TlgzSW1YSmhpVURyWHJHcTdmbXhEWW84eFdyWnVsc2g2dERhUGhXVWs2?= =?utf-8?B?SHZzS2N3c0hhdHord3h0Q1dsbnhPT3JMNEZmb2xyTEt3MFNFYlVWNEcyY0hp?= =?utf-8?B?dGJ1RjVEVlFZNG9ybnJUVHpUaTFLRldkWE1TTjdSeDVOa3ZhdXg1NHpTNnFW?= =?utf-8?B?Q1YyUGVzTTBNMkhyTkNEZVlBZEJJNStFcUI2YzhQVlBndDlmcEVPZzNZTDJx?= =?utf-8?B?WWtlRnRBNHhxMkYvaVdKMUJXcDBIR29aY3E1ekFIZ3RtUWpSMzVGTFlNcHR3?= =?utf-8?B?ZU1DZWxjQjFxNENJeWNPMThVRWVWQ3o4dFE0WDc2UytJdm9xejhIUWVpMEtG?= =?utf-8?B?UzhOMGFVKzJWc29PU09qQXBwV3dUNldsZUFBU2pQUHFVblRiM1hUU090NU1G?= =?utf-8?B?b1hJVVUrQVpaUElmMmlvK0lEdE93bFpNRmtYNkxGWCsvTm9sdDkrODZjTDZU?= =?utf-8?B?L3Y4ZW1UdnBGWWVlSmU0Ry9OeXFvY0J4bHJuOVBoaEp0YkhRTkJxTmVrWnV1?= =?utf-8?B?V3lZS2RMVkY2NUVVQXd5MjUvU3Qyci84Vm4rUXpQMTFmYUM3eGR0SUxBWGtH?= =?utf-8?Q?7/2spUU9rCg9a4vnEONCFJs=3D?= X-OriginatorOrg: os.amperecomputing.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1ba9933a-9f55-4a36-d22b-08dbf17fee39 X-MS-Exchange-CrossTenant-AuthSource: SN4PR01MB7455.prod.exchangelabs.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Nov 2023 08:39:56.8262 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3bc2b170-fd94-476d-b0ce-4229bdc904a7 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: yS0FznNfA++d7BvfiXnhfp0xhbnZx4MwDb2837VqOiM+LdJXu1pphfZ4o/hr92kzBwK64huNxtqNvx4JZyvUcDNdhJ3/pwCQ91xppJ6/rt8= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR01MB6560 On 30/11/2023 15:03, Jeremy Kerr wrote: > Hi Quan, > >> If arbitration is lost, __i2c_transfer() returns -EAGAIN and the >> packet should be resent. >> >> Requeue the packet and increase collisions count on this case. > > Are you sure you want to re-queue the packet here? The i2c core would > have already retried on arbitration loss: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/i2c/i2c-core-base.c#n2223 > > With this change, we would be disregarding the limits in adap->retries > and/or adap->timeout. > Yes, the __i2c_transfer() does try its best to send the packet but if it still fail with -EAGAIN, that means it still unable to win the arbitration. Without this patch we usually see the error below. The consequence is it stop and need the PLDM layer to retry when timed out, which takes time. "[ 61.616210] i2c i2c-3: __i2c_transfer failed -11" With this commit, we all see the packets go through peacefully just by requeueing the packets at MCTP layer and eliminated the need to retry in PLDM layer which would need more time. The result in our test is as below (Note: would needs some addition debug print code). I also think it is worth noting that in our setup there are multiple Masters. [73183.511487] i2c i2c-3: Arbitration loss, re-queue the packet [73192.550519] i2c i2c-3: __i2c_transfer failed -11 [73192.555734] i2c i2c-3: Arbitration loss, re-queue the packet [73207.250036] i2c i2c-3: __i2c_transfer failed -11 [73207.255247] i2c i2c-3: Arbitration loss, re-queue the packet [73429.499875] i2c i2c-3: __i2c_transfer failed -11 [73429.505116] i2c i2c-3: Arbitration loss, re-queue the packet [73504.672065] i2c i2c-3: __i2c_transfer failed -11 [73504.677317] i2c i2c-3: Arbitration loss, re-queue the packet [73540.762984] i2c i2c-3: __i2c_transfer failed -11 [73540.768242] i2c i2c-3: Arbitration loss, re-queue the packet [73631.040049] i2c i2c-3: __i2c_transfer failed -11 [73631.045333] i2c i2c-3: Arbitration loss, re-queue the packet [73648.538967] i2c i2c-3: __i2c_transfer failed -11 Thanks, - Quan