From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752209AbdGGQJx (ORCPT ); Fri, 7 Jul 2017 12:09:53 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:34061 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751854AbdGGQJc (ORCPT ); Fri, 7 Jul 2017 12:09:32 -0400 Date: Fri, 7 Jul 2017 18:08:52 +0200 From: Wim ten Have To: Sinan Kaya Cc: linux-pci@vger.kernel.org, timur@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Bjorn Helgaas , linux-kernel@vger.kernel.org, Wim ten Have Subject: Re: [PATCH V2] PCI: Do not enable extended tags on pre-dated (v1.x) systems Message-ID: <20170707180852.56b01e8b.wim.ten.have@oracle.com> In-Reply-To: <7d6e99b9-bdef-845a-a542-2c47f429eb12@codeaurora.org> References: <1499439193-16628-1-git-send-email-okaya@codeaurora.org> <7d6e99b9-bdef-845a-a542-2c47f429eb12@codeaurora.org> Organization: Oracle Corporation X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 7 Jul 2017 11:01:16 -0400 Sinan Kaya wrote: > Hi Wim, > > On 7/7/2017 10:53 AM, Sinan Kaya wrote: > > According to extended tags ECN document, all PCIe receivers are expected > > to support extended tags support. It should be safe to enable extended > > tags on endpoints without checking compatibility. > > > > This assumption seems to be working fine except for the legacy systems. > > The ECN has been written against PCIE spec version 2.0. Therefore, we need > > to exclude all version 1.0 devices from this change as there is HW out > > there that can't handle extended tags. > > > > Note that the default value of Extended Tags Enable bit is implementation > > specific. Therefore, we are clearing the bit by default when incompatible > > HW is found without assuming that value is zero. > > > > Reported-by: Wim ten Have > > Link: https://pcisig.com/sites/default/files/specification_documents/ECN_Extended_Tag_Enable_Default_05Sept2008_final.pdf > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=1467674 > > Fixes: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported") > > Signed-off-by: Sinan Kaya > > --- > > Can you also give this a spin? I don't have a system with v1 PCIe bridges. > I only tested v2 and later code path. > > I tried to address Jike Song concerns on this version and removed your tested-by > since the code changed. > > Sinan > Sure, -- Wim ten Have | Consulting Member of Technical Staff Oracle Linux and VM Development Engineering ORACLE Nederland BV | Hertogswetering 163-167 | 3543 AS Utrecht/NL