From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02BDDC43612 for ; Sat, 29 Dec 2018 19:18:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CAF76218A1 for ; Sat, 29 Dec 2018 19:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728173AbeL2TSP (ORCPT ); Sat, 29 Dec 2018 14:18:15 -0500 Received: from ale.deltatee.com ([207.54.116.67]:34852 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727944AbeL2TSO (ORCPT ); Sat, 29 Dec 2018 14:18:14 -0500 Received: from s0106602ad0811846.cg.shawcable.net ([68.147.191.165] helo=[192.168.0.12]) by ale.deltatee.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1gdK7Z-00050t-R7; Sat, 29 Dec 2018 12:18:06 -0700 To: Bjorn Helgaas , yu Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Stephen Bates , Jonathan Cameron , Eric Wehage , Alexander Duyck References: <20181229022923.GA159477@google.com> From: Logan Gunthorpe Message-ID: <2aa4d13a-83c5-7e15-261f-b8f69def5224@deltatee.com> Date: Sat, 29 Dec 2018 12:18:03 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181229022923.GA159477@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 68.147.191.165 X-SA-Exim-Rcpt-To: alexander.h.duyck@linux.intel.com, Eric.Wehage@huawei.com, jonathan.cameron@huawei.com, sbates@raithlin.com, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, kkndyu@gmail.com, helgaas@kernel.org X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: How to force RC to forward p2p TLPs X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-12-28 7:29 p.m., Bjorn Helgaas wrote: >> We use the p2p DMA to transfer data between these two endpoint SOCs, >> and if the host server is not enable ACS in BIOS, the p2p works well, >> but when ACS is enabled in BIOS, the p2p is always failed. With the >> help of a protocol analyzer, we can see that the TLP is redirected to >> RC, and RC just discard it. >> >> I tried to find how to make RC forward redirected TLP to its original >> target, but nothing found, it seems this is highly related to the RC >> vendors. As far as I know, this is not possible with any RCs I've worked with. For our work, we ensure we disable ACS on paths between peers that want to communicate. This is why we introduced the 'disable_acs_redir' kernel parameter[1] to selectively disable ACS for bridges along P2P paths. >> So is there some spec or document to describe how to set the RC? Any >> suggestion is appreciated. If there is, it would be the documentation for your specific RC. Odds are, the RC simply does not support this. Logan [1] https://patchwork.kernel.org/patch/10549279/