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 3A8ADC43460 for ; Mon, 26 Apr 2021 19:05:43 +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 98FF760E08 for ; Mon, 26 Apr 2021 19:05:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 98FF760E08 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 8D2826E1D7; Mon, 26 Apr 2021 19:05:41 +0000 (UTC) Received: from mail-vs1-f41.google.com (mail-vs1-f41.google.com [209.85.217.41]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0DE3D6E1D7 for ; Mon, 26 Apr 2021 19:05:41 +0000 (UTC) Received: by mail-vs1-f41.google.com with SMTP id h18so2170605vsp.8 for ; Mon, 26 Apr 2021 12:05:40 -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=1Z9q2q+by+XoICx7O5bq4s0qjl0Ui3wq+DFED5QpgnI=; b=hXBr1kVTJMXFkKuzfzhfndDGW3lXBiOnV7XdRrsPbh1iDPz06p4h7+6pY2rXreofzx zt9kCg2vMuD9+7yYDm2VjY7vtk4+XOZe5JFyUC3VwBasfX2jKLiFMxz+ywD4pr7lzjnz 0xMaVSCe59sSsAtr6tS6d3eojpCjxeWkwxF9WCGsF3HDUtElVDsOjeT2XdoK8+haw5ri SwUE/mn0Gf3eIRAqaIqne43aUdY6c8Ctu7TQGq/c4HELSrcJGwrpOhEyhriiX23zixk9 O+YR3J0q7kdHCOyGe+4n8KN6aheN9jwot47U20quxm4SgkMscJyw/MY9XK04aQsdGmb7 NtVA== X-Gm-Message-State: AOAM532hpvueLuMsCEMUldM8YAd0cPAvYjTDew7VfhPTwyjWgIs4mz6r AmGGc5F6SuB926ctVlS43tBIyse856JS/BdqvxM= X-Google-Smtp-Source: ABdhPJzFyKjW1O90Y0MBq25L4BoxSoh1eregzeBg4Y17kP7i6270tN+MexYhXLWOJPYKWPcRKKJuueNLlzEA80hUIcA= X-Received: by 2002:a67:8745:: with SMTP id j66mr14878201vsd.18.1619463940025; Mon, 26 Apr 2021 12:05:40 -0700 (PDT) MIME-Version: 1.0 References: <20210416090048.11492-1-tzimmermann@suse.de> <20210420092204.7azdb7nxgofegjht@sirius.home.kraxel.org> In-Reply-To: From: Geert Uytterhoeven Date: Mon, 26 Apr 2021 21:05:28 +0200 Message-ID: Subject: Re: [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs To: Thomas Zimmermann 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, "open list:DOCUMENTATION" , David Airlie , Greg KH , Jonathan Corbet , Emil Velikov , Liam Girdwood , DRI Development , virtualization@lists.linux-foundation.org, Hans de Goede , Mark Brown , Gerd Hoffmann , 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 Thomas, On Mon, Apr 26, 2021 at 2:22 PM Thomas Zimmermann wrote: > Am 20.04.21 um 11:27 schrieb Geert Uytterhoeven: > > On Tue, Apr 20, 2021 at 11:22 AM Gerd Hoffmann wrote: > >>>>> 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 > >>> 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. > >> > >> Well. cirrus converts xrgb8888 on the fly to rgb888 or rgb565 > >> (depending on display resolution). We could pull off the same trick > >> here and convert to rgb332 (assuming we can program the palette with the > >> color cube needed for that). Wouldn't look pretty, but would probably > >> work better than expecting userspace know what color palettes are in > >> 2021 ... > > > > Yeah, I already had a similar idea for Amiga HAM ;-) > > I vaguely remember that HAM mode uses some crazy format where pixel > colors depend in the values of their neighbors. (?) How complicated is > it to write a conversion from RGB to HAM? Not that complicated, unless you want to do it Good & Fast ;-) https://en.wikipedia.org/wiki/Hold-And-Modify 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