From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:60487 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755766AbcKVTGm (ORCPT ); Tue, 22 Nov 2016 14:06:42 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uAMHdVSl064135 for ; Tue, 22 Nov 2016 12:41:28 -0500 Received: from e06smtp06.uk.ibm.com (e06smtp06.uk.ibm.com [195.75.94.102]) by mx0b-001b2d01.pphosted.com with ESMTP id 26vku8tnct-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 22 Nov 2016 12:41:27 -0500 Received: from localhost by e06smtp06.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 22 Nov 2016 17:41:26 -0000 Subject: Re: [PATCH 2/2] cxl: Set VPD timeout to avoid access failures To: "Matthew R. Ochs" , Bjorn Helgaas , linux-pci@vger.kernel.org, Ian Munsie , linuxppc-dev@lists.ozlabs.org References: <1479762225-51440-1-git-send-email-mrochs@linux.vnet.ibm.com> <1479762606-51632-1-git-send-email-mrochs@linux.vnet.ibm.com> Cc: Uma Krishnan From: Frederic Barrat Date: Tue, 22 Nov 2016 18:41:22 +0100 MIME-Version: 1.0 In-Reply-To: <1479762606-51632-1-git-send-email-mrochs@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Message-Id: <05398bfe-5bd4-116b-a9d7-b974d4cc032a@linux.vnet.ibm.com> Sender: linux-pci-owner@vger.kernel.org List-ID: Le 21/11/2016 à 22:10, Matthew R. Ochs a écrit : > Some IBM CXL devices can take up to ~120ms to complete a VPD access > transaction when under heavy load. With an existing default VPD timeout > of 50ms, reads/writes can fail despite there not being an issue with the > underlying hardware. > > To avoid these false failures, increase the VPD wait timeout for certain > CXL devices to a value that allows appropriate VPD access delay when faced > with a worst-case scenario. > > Signed-off-by: Matthew R. Ochs > --- If the new pci API gets in, then I'm ok with the cxl change, at least for now. For longer term, we should consider opening up the cxl kernel API to give access to the new pci API so that it can be tuned by the AFU driver directly, since it would know better than cxl what the proper vpd access timeout should be. Acked-by: Frederic Barrat Fred