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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11D3BCCA480 for ; Tue, 12 Jul 2022 09:09:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232447AbiGLJJj (ORCPT ); Tue, 12 Jul 2022 05:09:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232129AbiGLJJc (ORCPT ); Tue, 12 Jul 2022 05:09:32 -0400 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17B0218398; Tue, 12 Jul 2022 02:09:30 -0700 (PDT) Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:b231:465::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4Lhw1M0SN3z9sWv; Tue, 12 Jul 2022 11:09:27 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1657616967; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7pHn6da070NlLkNZyZhpM0wryZYoHPMUzmHUsDvJrHQ=; b=ghsPRor69eTJP+6phIDt2wvIhwsbI8k+gAvUSsPResTnnCv3++NheO6kAXVnwf1L9XqzD0 jx5wXwS5XWpxtQPwTQ8jRpzb4hLxe28Y7E0qWzu6PPrSoPJ6jC47qLDVRc7bMfam6rvKjL hLUSNY/MAWepi3kpcD66XN0/8EwwBnS4dwzaWBeS4XJQNKn4BsZgFhz3Xn2Ga7ApaIgIn3 BCLMsEzbHPvE87AsUQrmwf5hbrZAYtKzlIlNoxtv6lTqhr7vl/MtYtu0V36uAmr9opMVUv SgEr5IobDwRyqMLIA7ShmmaaT5j9PIg+tiJriGG3b7JM0e/AST2gGX6lI+j+kQ== Message-ID: <69a6aac7-0d48-7361-9750-8f242d374d60@mailbox.org> Date: Tue, 12 Jul 2022 11:09:25 +0200 MIME-Version: 1.0 Subject: Re: [PATCH 1/3] drm/fourcc: Add missing big-endian XRGB1555 and RGB565 formats Content-Language: en-CA To: Gerd Hoffmann , Geert Uytterhoeven Cc: Linux Fbdev development list , Thomas Zimmermann , David Airlie , Linux/m68k , Linux Kernel Mailing List , =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= , DRI Development References: <0744671ac096a12f0d538906bd324efa71b11400.1657300532.git.geert@linux-m68k.org> <96a87833-d878-dde9-e335-9ea51a4ba406@mailbox.org> <20220712074715.kopstlvz4q6npaye@sirius.home.kraxel.org> <20220712083907.3ic7bltstaskz72n@sirius.home.kraxel.org> <20220712090305.44jq3olwhwypisoc@sirius.home.kraxel.org> From: =?UTF-8?Q?Michel_D=c3=a4nzer?= In-Reply-To: <20220712090305.44jq3olwhwypisoc@sirius.home.kraxel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-MBO-RS-ID: 9d87deff0c8c81f488c X-MBO-RS-META: 6fgaontf1ee3mo7o7bdra4eb1ym4h8t3 X-Rspamd-Queue-Id: 4Lhw1M0SN3z9sWv Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022-07-12 11:03, Gerd Hoffmann wrote: >>> As described above DRM_FORMAT_HOST_RGB565 means bigendian on bigendian >>> hosts and little endian on little endian hosts. Which is not correct >>> when your hardware does big endian no matter what. >> >> But (a) drm_driver_legacy_fb_format() uses DRM_FORMAT_HOST_RGB565 >> if quirk_addfb_prefer_host_byte_order is set, > > Ah, right. Missed that in 'git grep' output. Given that traditional > fbdev behavior is to expect native byte order using > DRM_FORMAT_HOST_RGB565 there makes sense indeed. > > Scratch my comment about it being unused then ;) DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN is still what the driver should use conceptually, and should match DRM_FORMAT_HOST_RGB565 in drm_driver_legacy_fb_format on a big endian host (which is presumably always the case for the atari driver). -- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and Xwayland developer