From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751135AbdEHAid (ORCPT ); Sun, 7 May 2017 20:38:33 -0400 Received: from mail.netline.ch ([148.251.143.178]:41189 "EHLO netline-mail3.netline.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751065AbdEHAic (ORCPT ); Sun, 7 May 2017 20:38:32 -0400 Subject: Re: [PATCH 1/3] drm: fourcc byteorder: drop DRM_FORMAT_BIG_ENDIAN To: Gerd Hoffmann Cc: Emil Velikov , open list , ML dri-devel , amd-gfx mailing list , Daniel Vetter References: <20170502133404.15354-1-kraxel@redhat.com> <20170502133404.15354-2-kraxel@redhat.com> <20170502172724.31188e2d@eldfell> <1493737591.8581.126.camel@redhat.com> <28424bad-95c8-7394-4742-cd258fd71032@daenzer.net> <1493803481.8581.163.camel@redhat.com> From: =?UTF-8?Q?Michel_D=c3=a4nzer?= Message-ID: Date: Mon, 8 May 2017 09:38:10 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <1493803481.8581.163.camel@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/05/17 06:24 PM, Gerd Hoffmann wrote: > Hi, > >>> R600+ supports bigendian framebuffer formats, so no byteswapping on >>> access is needed. Not sure whenever that includes 16bpp formats or >>> whenever this is limited to the 8 bit-per-color formats [...] >> >> It includes 16bpp. Looking at >> drivers/gpu/drm/radeon/atombios_crtc.c:dce4_crtc_do_set_base(), it sets >> up byte-swapping for all multi-byte formats, so it effectively treats >> all those formats as if they had DRM_FORMAT_BIG_ENDIAN set. > >> If the radeon (and amdgpu) driver were to be changed to use >> drm_mode_legacy_fb_format_he for >= R600, that must also handle 16 bpp, >> which requires DRM_FORMAT_BIG_ENDIAN. So I still don't see how that can >> be removed or even deprecated. > > Ok. > > Dropped patch #1. > > Updated patch #2 to include all formats returned by > drm_mode_legacy_fb_format, and also renamed them to DRM_FORMAT_HOST_*. > > Question is how to go forward with patch #3. I'd prefer to not add > drm_mode_legacy_fb_format_he if possible. Is there a chance to adapt > the radeon and nvidia drivers to a fixed drm_mode_legacy_fb_format > function (returning be formats on be) without invasive changes? Given > they both treat formats as if they had DRM_FORMAT_BIG_ENDIAN set this > could (with the help of the extended patch #2) be a simple > s/DRM_FORMAT_/DRM_FORMAT_HOST/ at the right places ... For radeon this doesn't work with pre-R600 GPUs, which only support little endian formats for display. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer