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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F2B17D6B6DB for ; Wed, 30 Oct 2024 21:20:13 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B82B810E0FD; Wed, 30 Oct 2024 21:20:13 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=deltatee.com header.i=@deltatee.com header.b="Hn4eDVf8"; dkim-atps=neutral Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) by gabe.freedesktop.org (Postfix) with ESMTPS id 406FE10E0FD; Wed, 30 Oct 2024 21:20:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:From:References:Cc:To: MIME-Version:Date:Message-ID:content-disposition; bh=Teay/SDFVQ3KrSrIP+rOxfqoHOvTS5vn0M/5NXbwQys=; b=Hn4eDVf8odnXEa3gXEbm04F6LU djR9gKjO57ul/d3FtdsFm/fG2y2ekwz4pJcTFtb+motJr/NBt6KmqAcxV1KLt9avHA0NOCJn3ZQSG r6jMjNFU9Gl1dPQdEIyeQBvvfO0FzNk+n7yvYYeX6zX4w9+Zk6e9fUyfJZRQDVT0ENZjJq1iyauLk 4WUBCye/WmytimX1SwUvQ/abqFWff76EZkjWUJfB40m2CiYFAQ4QHHdjNvfd3Shc7WQyJX7Df+rF2 0LDZaEyjmQt5/wRxxvWuw0CGBAoMcpQPWC0xG8j7oN5MsD4x44FzNPKvN+E9m0/M8lM2lKrzgWvDq 7MUw87PA==; Received: from d104-157-31-28.abhsia.telus.net ([104.157.31.28] helo=[192.168.1.250]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.96) (envelope-from ) id 1t6G6q-004Cg7-17; Wed, 30 Oct 2024 15:20:09 -0600 Message-ID: <7e146e2f-5d7c-4f28-b801-360795b4cae7@deltatee.com> Date: Wed, 30 Oct 2024 15:20:02 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Bjorn Helgaas , "Kasireddy, Vivek" Cc: "dri-devel@lists.freedesktop.org" , "intel-xe@lists.freedesktop.org" , Bjorn Helgaas , "linux-pci@vger.kernel.org" References: <20241030184641.GA1210322@bhelgaas> Content-Language: en-CA From: Logan Gunthorpe In-Reply-To: <20241030184641.GA1210322@bhelgaas> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 104.157.31.28 X-SA-Exim-Rcpt-To: helgaas@kernel.org, vivek.kasireddy@intel.com, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, bhelgaas@google.com, linux-pci@vger.kernel.org X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v2 1/5] PCI/P2PDMA: Don't enforce ACS check for functions of same device X-SA-Exim-Version: 4.2.1 (built Wed, 06 Jul 2022 17:57:39 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On 2024-10-30 12:46, Bjorn Helgaas wrote: > On Fri, Oct 25, 2024 at 06:57:37AM +0000, Kasireddy, Vivek wrote: > In the PCIe world, I don't think a TLP can "loop back" to another > function on the same device. I'm not sure if the spec says anything that specifically denies this. But it seems to me that it would be possible for a multifunction device to handle a transfer to a neighbouring function internally and not actually involve the PCIe fabric. This seems like something we'd want to support if and when such a device were to be created. Logan