From patchwork Fri Jul 8 18:20:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geert Uytterhoeven X-Patchwork-Id: 588746 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 B6BF9CCA488 for ; Fri, 8 Jul 2022 18:21:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239163AbiGHSVS (ORCPT ); Fri, 8 Jul 2022 14:21:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239096AbiGHSVP (ORCPT ); Fri, 8 Jul 2022 14:21:15 -0400 Received: from laurent.telenet-ops.be (laurent.telenet-ops.be [IPv6:2a02:1800:110:4::f00:19]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F00C082396 for ; Fri, 8 Jul 2022 11:21:10 -0700 (PDT) Received: from ramsan.of.borg ([84.195.186.194]) by laurent.telenet-ops.be with bizsmtp id siM7270094C55Sk01iM7mo; Fri, 08 Jul 2022 20:21:08 +0200 Received: from rox.of.borg ([192.168.97.57]) by ramsan.of.borg with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1o9sbC-002fGb-Lh; Fri, 08 Jul 2022 20:21:06 +0200 Received: from geert by rox.of.borg with local (Exim 4.93) (envelope-from ) id 1o9sbC-00BtJ3-7L; Fri, 08 Jul 2022 20:21:06 +0200 From: Geert Uytterhoeven To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-m68k@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH v3 00/10] drm: Add support for low-color frame buffer formats Date: Fri, 8 Jul 2022 20:20:45 +0200 Message-Id: X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Hi all, A long outstanding issue with the DRM subsystem has been the lack of support for low-color displays, as used typically on older desktop systems, and on small embedded displays. This patch series adds support for color-indexed frame buffer formats with 2, 4, and 16 colors. It has been tested on ARAnyM using a work-in-progress Atari DRM driver supporting 2, 4, 16, 256, and 65536 colors, with text console operation, fbtest, and modetest. Overview: - Patch 1 introduces a helper, to be used by later patches in the series, - Patch 2 introduces a flag to indicate color-indexed formats, - Patches 3 and 4 correct calculations of bits per pixel for sub-byte pixel formats, - Patches 5 and 6 introduce the new C[124] formats, - Patch 7 fixes an untested code path, - Patch 8 documents the use of "red" for light-on-dark displays, - Patches 9 and 10 add more fourcc codes for light-on-dark and dark-on-light frame buffer formats, which may be useful for e.g. the ssd130x and repaper drivers. Changes compared to v2[1]: - Add Reviewed-by, - Document fill order, - Fix FB_VISUAL_TRUECOLOR, - Replace light-on-dark/dark-on-light by direct/inverse relationship between channel value and brightness. Changes compared to v1[2]: - Reshuffle patches, - New patch "[PATCH v2 02/10] drm/fourcc: Add drm_format_info.is_color_indexed flag", - Improve pixel descriptions, - Require depth to match bpp in drm_mode_legacy_fb_format(), - Set .is_color_indexed flag. - Use drm_format_info_bpp() helper instead of deprecated .depth field or format-dependent calculations, - Use new .is_color_indexed field instead of checking against a list of formats, - Add Acked-by, - Replace FIXME by TODO comment, - New patch "[PATCH v2 08/10] [RFC] drm/fourcc: Document that single-channel "red" can be any color", - Add rationale for adding new formats, - Add D[248] for completeness. Notes: - This is the first patch series in a series of 3: - To make high-color modes work on big-endian, you also need [3], - To make mode selection on the command line work for Atari video modes, you need [4]. - There is also a related series of 3 patch series for modetest: - Using modetest with low-color formats (C[124]) requires [5], - Using modetest with high-color formats (RG16, XR24) requires [6], - Using modetest with video mode names containing dashes requires [7]. - As this was used on emulated hardware only, and I do not have Atari hardware, I do not have performance figures to compare with fbdev. I hope to do proper measuring with an Amiga DRM driver, eventually. - While the Atari DRM driver is not fit for submission yet, you can find it at [8], if you are adventurous. Thanks for your comments! [1] "[PATCH v2 00/10] drm: Add support for low-color frame buffer formats" https://lore.kernel.org/r/cover.1646683502.git.geert@linux-m68k.org/ [2] "[PATCH 0/8] drm: Add support for low-color frame buffer formats" https://lore.kernel.org/r/20220215165226.2738568-1-geert@linux-m68k.org/ [3] "[PATCH 0/3] drm: Endianness fixes" https://lore.kernel.org/r/cover.1657300532.git.geert@linux-m68k.org [4] "[PATCH 0/5] drm/modes: Command line mode selection fixes and improvements" https://lore.kernel.org/r/cover.1657301107.git.geert@linux-m68k.org [5] "[PATCH libdrm v2 00/10] Add support for low-color frame buffer formats" https://lore.kernel.org/r/cover.1657302034.git.geert@linux-m68k.org [6] "[PATCH libdrm v2 00/10] Big-endian fixes" https://lore.kernel.org/r/cover.1657302103.git.geert@linux-m68k.org [7] "[PATCH libdrm] modetest: Add support for named modes containing dashes" [8] https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/log/?h=atari-drm-wip Geert Uytterhoeven (10): drm/fourcc: Add drm_format_info_bpp() helper drm/fourcc: Add drm_format_info.is_color_indexed flag drm/client: Use actual bpp when allocating frame buffers drm/framebuffer: Use actual bpp for DRM_IOCTL_MODE_GETFB drm/fourcc: Add DRM_FORMAT_C[124] drm/fb-helper: Add support for DRM_FORMAT_C[124] drm/gem-fb-helper: Use actual bpp for size calculations drm/fourcc: Clarify the meaning of single-channel "red" [RFC] drm/fourcc: Add DRM_FORMAT_R[124] [RFC] drm/fourcc: Add DRM_FORMAT_D[1248] drivers/gpu/drm/drm_client.c | 4 +- drivers/gpu/drm/drm_fb_helper.c | 101 ++++++++++++++----- drivers/gpu/drm/drm_fourcc.c | 55 +++++++++- drivers/gpu/drm/drm_framebuffer.c | 2 +- drivers/gpu/drm/drm_gem_framebuffer_helper.c | 12 +-- include/drm/drm_fourcc.h | 4 + include/uapi/drm/drm_fourcc.h | 32 +++++- 7 files changed, 167 insertions(+), 43 deletions(-) Acked-by: Thomas Zimemrmann