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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 6DBCFC433ED for ; Tue, 20 Apr 2021 09:16:25 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D36336127C for ; Tue, 20 Apr 2021 09:16:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D36336127C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 18A626E4E3; Tue, 20 Apr 2021 09:16:24 +0000 (UTC) Received: from mail-vs1-f44.google.com (mail-vs1-f44.google.com [209.85.217.44]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6394A6E4D0 for ; Tue, 20 Apr 2021 09:16:22 +0000 (UTC) Received: by mail-vs1-f44.google.com with SMTP id d25so12389928vsp.1 for ; Tue, 20 Apr 2021 02:16:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uP55GvNxmqa154x7zBMI5pifzTMvppax2nMlHT01uhQ=; b=iTQnWMSmV5Ypl14cE07CFSPT3vDE7nSY7hFhwpDoEgzrh/voYkuD6GQ/1yTpu7iOZ2 ynQdKht6tmhIdQ4AES5+Xd7tASMvsbbSf8EDl7CFAyFB6Hj7KpNfzBgWMjj/yTbSRjtt bbsX2AscUD5ukE8h45W0JvJ/DHr6vDA6Rn8zsSO9YE4T2meDqiE+W6RlK7+f/CvQWxeH HgRMVN+YIH20z/QZvZvbJ8RKsxdLn77w9QtWZ55wTPBAFTAD6oF3Ulve4YV2PVOR42FO 8zBGRMi2A4rkPGeXx+StZh1sdla/2I3Px2GlRnIZhftRRrbIITz1lL31r9bSON7T49yR IXHg== X-Gm-Message-State: AOAM533XSx6XDNitLEJE9fR95nlLWZTsXKhWOeCKn+az8mA2l6QDZ3az +id+VsGhuyYhyKyOfAhSSlxxSCuupOsppGY0UMA= X-Google-Smtp-Source: ABdhPJyqjmGX3OnB4biL5E0m5o4GJ98N03BW81GWgSF08q3NwpxNGSQhoujnYb0pAPeIay+ye8/EKvIXD8MRF5C4Bbw= X-Received: by 2002:a67:fc57:: with SMTP id p23mr19084812vsq.40.1618910181231; Tue, 20 Apr 2021 02:16:21 -0700 (PDT) MIME-Version: 1.0 References: <20210416090048.11492-1-tzimmermann@suse.de> In-Reply-To: From: Geert Uytterhoeven Date: Tue, 20 Apr 2021 11:16:09 +0200 Message-ID: Subject: Re: [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs To: Daniel Vetter X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bluescreen_avenger@verizon.net, Jonathan Corbet , David Airlie , Emil Velikov , DRI Development , "open list:DOCUMENTATION" , Liam Girdwood , virtualization@lists.linux-foundation.org, Hans de Goede , Mark Brown , Gerd Hoffmann , Thomas Zimmermann , Greg KH , Sam Ravnborg Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Daniel, On Tue, Apr 20, 2021 at 10:46 AM Daniel Vetter wrote: > On Mon, Apr 19, 2021 at 10:00:56AM +0200, Geert Uytterhoeven wrote: > > On Fri, Apr 16, 2021 at 11:00 AM Thomas Zimmermann wrote: > > > This patchset adds support for simple-framebuffer platform devices and > > > a handover mechanism for native drivers to take-over control of the > > > hardware. > > > > > > The new driver, called simpledrm, binds to a simple-frambuffer platform > > > device. The kernel's boot code creates such devices for firmware-provided > > > framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot > > > loader sets up the framebuffers. Description via device tree is also an > > > option. > > > > I guess this can be used as a replacement for offb, too... > > > > > Patches 4 to 8 add the simpledrm driver. It's build on simple DRM helpers > > > and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During > > > > .... if support for 8-bit frame buffers would be added? > > Is that 8-bit greyscale or 8-bit indexed with 256 entry palette? Former 8-bit indexed with 256 entry palette. > shouldn't be a big thing, but the latter is only really supported by the > overall drm ecosystem in theory. Most userspace assumes that xrgb8888 > works, and we keep that illusion up by emulating it in kernel for hw which > just doesn't support it. But reformatting xrgb8888 to c8 is tricky at > best. The uapis are all there for setting the palette, and C8 is a defined > format even with atomic kms interface, but really there's not much > userspace for it. In other words, it would work as well as current offb > would, but that's at least that. Oh, that's good to know! Does this mean fbdev is not deprecated for anything <= C8? ;-) A while ago, I was looking into converting an fbdev driver to drm, and one of the things I ran into is lack of C4, C2, C1, Y8, Y4, Y2, and monochrome support. On top of that, lots of internal code seems to assume pixels are never smaller than a byte (thus ignoring char_per_block[]/block_w). The lack of support for planar modes isn't that bad, combined with the need for copying, as c2p conversion can be done while copying, thus even making life easier for userspace applications that can just always work on chunky data. Then real work kicked in, before I got anything working... Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel