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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 5047CC43334 for ; Tue, 4 Sep 2018 08:00:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3A5E20867 for ; Tue, 4 Sep 2018 08:00:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F3A5E20867 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=daenzer.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726213AbeIDMYa (ORCPT ); Tue, 4 Sep 2018 08:24:30 -0400 Received: from mail.netline.ch ([148.251.143.178]:49217 "EHLO netline-mail3.netline.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725990AbeIDMY3 (ORCPT ); Tue, 4 Sep 2018 08:24:29 -0400 Received: from localhost (localhost [127.0.0.1]) by netline-mail3.netline.ch (Postfix) with ESMTP id 90EA12A6042; Tue, 4 Sep 2018 10:00:28 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at netline-mail3.netline.ch Received: from netline-mail3.netline.ch ([127.0.0.1]) by localhost (netline-mail3.netline.ch [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 1wKgb2755Kyt; Tue, 4 Sep 2018 10:00:28 +0200 (CEST) Received: from thor (67.124.127.176.dynamic.wline.res.cust.swisscom.ch [176.127.124.67]) by netline-mail3.netline.ch (Postfix) with ESMTPSA id D55662A604A; Tue, 4 Sep 2018 10:00:27 +0200 (CEST) Received: from localhost ([::1]) by thor with esmtp (Exim 4.91) (envelope-from ) id 1fx6GB-0007Al-Hz; Tue, 04 Sep 2018 10:00:27 +0200 Subject: Re: [PATCH 3/5] drm: fix drm_mode_addfb() on big endian machines. To: Ilia Mirkin , Gerd Hoffmann , David Airlie , Sean Paul References: <20180903105756.24912-1-kraxel@redhat.com> <20180903105756.24912-4-kraxel@redhat.com> <20180903164558.GL21634@phenom.ffwll.local> Cc: dri-devel , open list From: =?UTF-8?Q?Michel_D=c3=a4nzer?= Openpgp: preference=signencrypt Autocrypt: addr=michel@daenzer.net; prefer-encrypt=mutual; keydata= mQGiBDsehS8RBACbsIQEX31aYSIuEKxEnEX82ezMR8z3LG8ktv1KjyNErUX9Pt7AUC7W3W0b LUhu8Le8S2va6hi7GfSAifl0ih3k6Bv1Itzgnd+7ZmSrvCN8yGJaHNQfAevAuEboIb+MaVHo 9EMJj4ikOcRZCmQWw7evu/D9uQdtkCnRY9iJiAGxbwCguBHtpoGMxDOINCr5UU6qt+m4O+UD /355ohBBzzyh49lTj0kTFKr0Ozd20G2FbcqHgfFL1dc1MPyigej2gLga2osu2QY0ObvAGkOu WBi3LTY8Zs8uqFGDC4ZAwMPoFy3yzu3ne6T7d/68rJil0QcdQjzzHi6ekqHuhst4a+/+D23h Za8MJBEcdOhRhsaDVGAJSFEQB1qLBACOs0xN+XblejO35gsDSVVk8s+FUUw3TSWJBfZa3Imp V2U2tBO4qck+wqbHNfdnU/crrsHahjzBjvk8Up7VoY8oT+z03sal2vXEonS279xN2B92Tttr AgwosujguFO/7tvzymWC76rDEwue8TsADE11ErjwaBTs8ZXfnN/uAANgPLQjTWljaGVsIERh ZW56ZXIgPG1pY2hlbEBkYWVuemVyLm5ldD6IXgQTEQIAHgUCQFXxJgIbAwYLCQgHAwIDFQID AxYCAQIeAQIXgAAKCRBaga+OatuyAIrPAJ9ykonXI3oQcX83N2qzCEStLNW47gCeLWm/QiPY jqtGUnnSbyuTQfIySkK5AQ0EOx6FRRAEAJZkcvklPwJCgNiw37p0GShKmFGGqf/a3xZZEpjI qNxzshFRFneZze4f5LhzbX1/vIm5+ZXsEWympJfZzyCmYPw86QcFxyZflkAxHx9LeD+89Elx bw6wT0CcLvSv8ROfU1m8YhGbV6g2zWyLD0/naQGVb8e4FhVKGNY2EEbHgFBrAAMGA/0VktFO CxFBdzLQ17RCTwCJ3xpyP4qsLJH0yCoA26rH2zE2RzByhrTFTYZzbFEid3ddGiHOBEL+bO+2 GNtfiYKmbTkj1tMZJ8L6huKONaVrASFzLvZa2dlc2zja9ZSksKmge5BOTKWgbyepEc5qxSju YsYrX5xfLgTZC5abhhztpYhGBBgRAgAGBQI7HoVFAAoJEFqBr45q27IAlscAn2Ufk2d6/3p4 Cuyz/NX7KpL2dQ8WAJ9UD5JEakhfofed8PSqOM7jOO3LCA== Message-ID: <8e8f8cf3-c4d4-6bfd-4e53-536d4d0c79ff@daenzer.net> Date: Tue, 4 Sep 2018 10:00:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-09-03 7:07 p.m., Ilia Mirkin wrote: > On Mon, Sep 3, 2018 at 12:45 PM, Daniel Vetter wrote: >> On Mon, Sep 03, 2018 at 12:57:54PM +0200, Gerd Hoffmann wrote: >>> Userspace on big endian machhines typically expects the ADDFB ioctl >>> returns a big endian framebuffer. drm_mode_addfb() will call >>> drm_mode_addfb2() unconditionally with little endian DRM_FORMAT_* >>> values though, which is wrong. This patch fixes that. >>> >>> Drivers (both kernel and xorg) have quirks in place to deal with the >>> broken drm_mode_addfb() behavior. Because of this we can't just change >>> drm_mode_addfb() behavior for everybody without breaking things. So add >>> a new driver feature flag DRIVER_PREFER_HOST_BYTE_ORDER, so drivers can >>> opt-in. >>> >>> Signed-off-by: Gerd Hoffmann >>> --- >>> include/drm/drm_drv.h | 1 + >>> drivers/gpu/drm/drm_framebuffer.c | 11 +++++++++++ >>> 2 files changed, 12 insertions(+) >>> >>> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h >>> index 46a8009784..9cf12596cd 100644 >>> --- a/include/drm/drm_drv.h >>> +++ b/include/drm/drm_drv.h >>> @@ -57,6 +57,7 @@ struct drm_printer; >>> #define DRIVER_KMS_LEGACY_CONTEXT 0x20000 >>> #define DRIVER_SYNCOBJ 0x40000 >>> #define DRIVER_PREFER_XBGR_30BPP 0x80000 >>> +#define DRIVER_PREFER_HOST_BYTE_ORDER 0x100000 >> >> Hm, not a huge fan of using driver_flags for random little quirks. I think >> a boolean in sturct drm_mode_config would be much better. Bonus if you >> also move the 30bpp hack over to that. Something like >> mode_config.quirk_addfb_host_byte_order and >> mode_config.quirk_addfb_prefer_xbgr_30bpp or whatever. That has the upside >> of giving us a really nice place to put a huge comment about what this is >> supposed to do. >> >> I think otherwise this looks overall rather reasonable. I think the only >> other driver that ever cared about big endian was radeon/amdgpu. Would be >> good to get at least an ack from amd folks, or a "meh, stopped caring". > > and nouveau. > > I do believe that ADDFB should be made to always prefer host byte > order -- this is how all of the existing implementations work in > practice. However e.g. nouveau wants DRM_FORMAT_XRGB8888. But it still > treats it as host byte order. This will become more important in a > world where ADDFB2 is more common. > > So, I think that this change should be applied, drivers (I suspect > just nouveau and radeon) fixed up to consume the "new" formats, [...] As explained before, that would break radeon userspace on big endian hosts. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer