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Received: from DS0PR12MB7630.namprd12.prod.outlook.com (2603:10b6:8:11d::6) by CH2PR12MB4326.namprd12.prod.outlook.com (2603:10b6:610:af::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9499.7; Thu, 15 Jan 2026 21:55:15 +0000 Received: from DS0PR12MB7630.namprd12.prod.outlook.com ([fe80::c81a:611d:7325:7744]) by DS0PR12MB7630.namprd12.prod.outlook.com ([fe80::c81a:611d:7325:7744%2]) with mapi id 15.20.9520.005; Thu, 15 Jan 2026 21:55:15 +0000 Message-ID: <080d7aef-0139-4da4-8f43-aedbf9bb9948@nvidia.com> Date: Thu, 15 Jan 2026 13:55:09 -0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] PCI: Mark Nvidia GB10 to avoid bus reset To: Bjorn Helgaas Cc: =?UTF-8?B?Sm9obm55LUNDIENoYW5nICjlvLXmmYvlmIkp?= , "lukas@wunner.de" , Project_Global_Digits_Upstream_Group , AngeloGioacchino Del Regno , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-pci@vger.kernel.org" , "linux-mediatek@lists.infradead.org" , "bhelgaas@google.com" , "matthias.bgg@gmail.com" , Jason Gunthorpe , Alex Williamson References: <20260115205347.GA881345@bhelgaas> Content-Language: en-US From: Terje Bergstrom In-Reply-To: <20260115205347.GA881345@bhelgaas> Content-Type: text/plain; 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That's right. The symptoms can vary, i.e. sometimes it retrains with lower lane count, and sometimes config reads start timing out, and very often it works just fine. > I see you're from NVIDIA, so if you're confirming that this is a > hardware erratum (not an issue with the GB10 PCI controller driver), > we should definitely apply this, and I'll wordsmith the commit log > and comment something like this: > > When asserting Secondary Bus Reset to downstream devices via a GB10 > Root Port, the link doesn't retrain correctly. The link may retrain > with a lower lane count, and config accesses to downstream devices > may fail. Yes, I confirm this is a HW erratum. The problem doesn't occur every time, so "the link may not retrain correctly" would be more correct, but that's a minor comment. Terje