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=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 E4538C433E0 for ; Fri, 24 Jul 2020 15:06:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C27D620737 for ; Fri, 24 Jul 2020 15:06:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595603204; bh=d/lHftCugyAGXbmWZxAljFlvx4t6XIizbWGk9XJGek8=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=BwMFBRGAGOEzj1t2/hWMOufPw3Gl5VM6GDehtfOtMuKuRuJwMiKbkTXW1Y/ew0abA 8SoIZzLjf6xnRVCVhT+HAsgyrj2Lhrxw+M3cZdXsjHLOO/R/n1Z6D5bZe9L0VjwTmx NcUw26inGKGY9vIOHWkx0GKqKbFmv/H37VxDYm4s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726782AbgGXPGn (ORCPT ); Fri, 24 Jul 2020 11:06:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:40388 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726424AbgGXPGn (ORCPT ); Fri, 24 Jul 2020 11:06:43 -0400 Received: from localhost (mobile-166-175-191-139.mycingular.net [166.175.191.139]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7B81120714; Fri, 24 Jul 2020 15:06:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595603202; bh=d/lHftCugyAGXbmWZxAljFlvx4t6XIizbWGk9XJGek8=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=YsjxJOVkT3utZoAopAiM9AzCy9/gsq8e90vIYnS8HCmi3TKoHyfjf4ovxvridIluu oK0BfZXwVAPelnhcd/bQh4flU8Kxyvq1XaJ5KmGJEvPaAPjLA+qA8kgJPKYnLQdIfr rDiTawY8yno4O21e5vcgirMSF5vKuAezym4//HAk= Date: Fri, 24 Jul 2020 10:06:41 -0500 From: Bjorn Helgaas To: Logan Gunthorpe Cc: Alex Deucher , LKML , Linux PCI , Bjorn Helgaas , Christian =?iso-8859-1?Q?K=F6nig?= , Huang Rui , Andrew Maier , "H. Peter Anvin" Subject: Re: [PATCH] PCI/P2PDMA: Add AMD Zen 2 root complex to the list of allowed bridges Message-ID: <20200724150641.GA1518875@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <89d853d1-9e45-1ba5-5be7-4bbce79c7fb8@deltatee.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 23, 2020 at 02:10:52PM -0600, Logan Gunthorpe wrote: > On 2020-07-23 1:57 p.m., Bjorn Helgaas wrote: > > On Thu, Jul 23, 2020 at 02:01:17PM -0400, Alex Deucher wrote: > >> On Thu, Jul 23, 2020 at 1:43 PM Logan Gunthorpe wrote: > >>> > >>> The AMD Zen 2 root complex (Starship/Matisse) was tested for P2PDMA > >>> transactions between root ports and found to work. Therefore add it > >>> to the list. > >>> > >>> Signed-off-by: Logan Gunthorpe > >>> Cc: Bjorn Helgaas > >>> Cc: Christian König > >>> Cc: Huang Rui > >>> Cc: Alex Deucher > >> > >> Starting with Zen, all AMD platforms support P2P for reads and writes. > > > > What's the plan for getting out of the cycle of "update this list for > > every new chip"? Any new _DSMs planned, for instance? > > Well there was an effort to add capabilities in the PCI spec to describe > this but, as far as I know, they never got anywhere, and hardware still > doesn't self describe with this. Any idea what happened? Is there hope for the future? I'm really not happy about signing up for open-ended device-specific patches like this. It's certainly not in the plug and play spirit that has made PCI successful. I know, preaching to the choir here. Bjorn