From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932330AbeCKTv3 (ORCPT ); Sun, 11 Mar 2018 15:51:29 -0400 Received: from mx0b-00272701.pphosted.com ([208.86.201.61]:47646 "EHLO mx0b-00272701.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932161AbeCKTv0 (ORCPT ); Sun, 11 Mar 2018 15:51:26 -0400 Date: Sun, 11 Mar 2018 14:51:16 -0500 From: Nick French To: Andy Lutomirski Cc: "Luis R. Rodriguez" , Andy Lutomirski , "hans.verkuil@cisco.com" , "linux-kernel@vger.kernel.org" , "linux-media@vger.kernel.org" Subject: Re: ivtv: use arch_phys_wc_add() and require PAT disabled Message-ID: <20180311195116.GB4645@tivo.lan> References: <20180301171936.GU14069@wotan.suse.de> <20180307190205.GA14069@wotan.suse.de> <20180308040601.GQ14069@wotan.suse.de> <20180308041411.GR14069@wotan.suse.de> <67E7293F-6045-4EA1-8AEF-E4B92E046581@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <67E7293F-6045-4EA1-8AEF-E4B92E046581@amacapital.net> User-Agent: Mutt/1.9.1 (2017-09-22) X-Originating-IP: [155.94.246.64] X-ClientProxiedBy: SN4PR0501CA0103.namprd05.prod.outlook.com (2603:10b6:803:42::20) To CY4PR03MB3029.namprd03.prod.outlook.com (2603:10b6:903:132::17) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 60027eea-61e3-4aa5-a5ff-08d587897688 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(8989060)(5600026)(4604075)(4534165)(7168020)(4627221)(201703031133081)(201702281549075)(8990040)(2017052603328)(7167020)(7153060)(7193020);SRVR:CY4PR03MB3029; 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I haven't experience any problems running >> with PAT-enabled and no write-combining on the framebuffer. Any objections? >> > > None from me. > > However, since you have the hardware, you could see if you can use the > change_page_attr machinery to change the memory type on the framebuffer once > you figure out where it is. I am certainly willing to try this, but my understanding of the goal of the changes that disabled ivtvfb originally is that it was trying to hide the architecture-specific memory management from the driver. Wouldn't (figuring out a way to) expose x86/mm/pageattr internals to the driver be doing the opposite? (or maybe I misunderstand your suggestion) - Nick