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=-11.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5BCA4C4338F for ; Wed, 4 Aug 2021 23:52:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2EE1D60F38 for ; Wed, 4 Aug 2021 23:52:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235877AbhHDXw0 (ORCPT ); Wed, 4 Aug 2021 19:52:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:49964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234280AbhHDXw0 (ORCPT ); Wed, 4 Aug 2021 19:52:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7238B60E74; Wed, 4 Aug 2021 23:52:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628121132; bh=GaUVR4F7f+sFzr/xkqgZ6fCsqAi65wnqE2WixQ1qK7M=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=FAAsayDdUZFt250jNPqVXgM2siua7E14+TF048p066UrjDZUaR3gVg+vcFfja+NLK tBNtFYS+Wmw53OnQbXPKTVeUKuZby9g6G494T1irxUrAQBhFyuBogx5vaDrrSG0U4s HhpOG+4i291MFDsPxqX31o5qVLQYb0arydLQJ6wE0/B8ywm/zgh65u0TyOQyS4wNcB OxkMBPMprre4WOLZVo+u375oUwwN0BZdjENTYVkm+rTGYDiaSJjkGSWIyYKjW3G2MM Veg4uuVFOUgwYtaAtNSY0B3+1yNxOSkD0iDLoiSCRK8nQ0GOLlJfOj/39rvdAtXGpG F7cR0CSlFwZaw== Date: Wed, 4 Aug 2021 18:52:11 -0500 From: Bjorn Helgaas To: Dongdong Liu Cc: hch@infradead.org, kw@linux.com, logang@deltatee.com, leon@kernel.org, linux-pci@vger.kernel.org, rajur@chelsio.com, hverkuil-cisco@xs4all.nl, linux-media@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH V7 7/9] PCI/sysfs: Add a 10-Bit Tag sysfs file Message-ID: <20210804235211.GA1693993@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1628084828-119542-8-git-send-email-liudongdong3@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Wed, Aug 04, 2021 at 09:47:06PM +0800, Dongdong Liu wrote: > PCIe spec 5.0 r1.0 section 2.2.6.2 says that if an Endpoint supports > sending Requests to other Endpoints (as opposed to host memory), the > Endpoint must not send 10-Bit Tag Requests to another given Endpoint > unless an implementation-specific mechanism determines that the Endpoint > supports 10-Bit Tag Completer capability. Add a 10bit_tag sysfs file, > write 0 to disable 10-Bit Tag Requester when the driver does not bind > the device if the peer device does not support the 10-Bit Tag Completer. > This will make P2P traffic safe. the 10bit_tag file content indicate > current 10-Bit Tag Requester Enable status. > > Signed-off-by: Dongdong Liu > + The file is also writeable, the value only accept by write 0 > + to disable 10-Bit Tag Requester when the driver does not bind > + the deivce. The typical use case is for p2pdma when the peer > + device does not support 10-BIT Tag Completer. s/10-BIT/10-Bit/