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 89F84C433FE for ; Tue, 18 Jan 2022 10:14:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237002AbiARKOU (ORCPT ); Tue, 18 Jan 2022 05:14:20 -0500 Received: from mout.gmx.net ([212.227.17.20]:47529 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229514AbiARKOT (ORCPT ); Tue, 18 Jan 2022 05:14:19 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1642500847; bh=q9WeE4nIkI5prnRwCwlCoEZMzm5Vu8F3aRRX9wup85I=; h=X-UI-Sender-Class:Date:Subject:To:Cc:References:From:In-Reply-To; b=kgH/k0fgUR+sfgPujSr97qtwglOnKEUKTUSoRg76ufdwAZF/APGcdx9vIa2eSXML4 HC+V8cZAKQ+jfprpH3YntF3qDk15JNauwh0grwiN9os6JZCDgedwpgFuz4wDxLOaOh RsuBSODvV4fZe2Mms034aWfgGNJ9o2CSX/2Msk9k= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [192.168.20.60] ([92.116.155.155]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1M3lcJ-1n9UNw2bdD-000xTZ; Tue, 18 Jan 2022 11:14:07 +0100 Message-ID: Date: Tue, 18 Jan 2022 11:13:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer Content-Language: en-US To: Gerd Hoffmann Cc: Daniel Vetter , Linux Fbdev development list , Sven Schnelle , Linux Kernel Mailing List , DRI Development , Javier Martinez Canillas , Geert Uytterhoeven , Thomas Zimmermann , Linus Torvalds References: <20220117125716.yjwxsze35j2ndn2i@sirius.home.kraxel.org> <70530b62-7b3f-db88-7f1a-f89b824e5825@suse.de> <57d276d3-aa12-fa40-6f90-dc19ef393679@gmx.de> <20220118062947.6kfuam6ah63z5mmn@sirius.home.kraxel.org> <20220118091615.3ih5n7vhd6tgmnku@sirius.home.kraxel.org> From: Helge Deller In-Reply-To: <20220118091615.3ih5n7vhd6tgmnku@sirius.home.kraxel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:GSa5Cuwffr03edaVa0sJSU9YmqnXcHnWJIo9Ct+Ij/irNGRZHOQ x9iouiO+a8hYt5WQoc46evDp9gebCfSWQwXISLFU0xTkDDqpwnZ1njRykOejpKWcnRmjV8m 77sippyRY+i6o2mdu4Sv51buqcd0gDGbvi3lYHEBaCn3x4J8/1CQX7SKM6eS1LMOl1FB9+x ziz/DNQ+7TRiJldahe2QA== X-UI-Out-Filterresults: notjunk:1;V03:K0:ZcWvDr5nQG0=:hXj3r+EYoT1FLW3XVX1xee wmrFQX+Eubm79xJAn5dZelAxnVm3TQ46yC5misZfEnDb16jpVhrQWMJYBOBvxWE8Bykq3Uezt ZHuL2K9VitLiQpu5Ydz4vZAJ1BfaiZBYC8wcnCCQ2wMk12IWXl2uuJgdoWjQpHrLvXQMuZ8Dq ltofp0ZYpkpeck6XDoKj4I61/gq97IXthQ9G+aQHPXov1FaI3vIcPPGeXth6iu9dKUQRUjfkv v9XHCfHVFWVn/5tczHCHTurJeL3lofzsbJjGmkdTkwDN5Uqt77wpU9s3JB6m6yznfpSMVOCOu IKhKYVVpIN4y4uTfdmEKoTGudc7o/lgrGbKu0Cxx+KGMmzaK8iD99U5tPXdY65KvBb6M3YWa3 mgWJoSKfN13LT1ygBKG+U6f5P70Uy9OJNut66tS/hDoyTMx93aYzr1JZkWlrOpEsaVVD340tr Dm7nqEAXUJP4TFqZ2BSsA7W8Nk3bUQjJY6Wy0LuCsktYYKpkgnub5o2QIdpCWQM64zbIY8w5q ROQxbWwgdA8mkGn5U3WN+QeDpSay+HN1UBMGpSXlWLbE2DSf5To7aNY0gh9JH/uXUEgvTEvy9 3OEnzmxoRJXQZn9g2ioUMKVXxcIEwG0gq7z+aLR6d++6o/fmJbS6P13UdC4tiBuGTPrS72hzT SQd0rh1lFNxxvxYxJkA2peVXCLb5wGAF/uUHB5I95oBt0Rknq0VaU0lEms3oEuXFOpUATbPIA ulRthweN18ZJVXkn8JLdWLO/qV/ttxRS+fkt95VGiUfUSEheLMLGspNrE2cTZfQfB88dYWQFn MI3fxHpb3ODd8/bd6YF58z+40UTuU4DfsgT8UdaUHwG2Fn0Sp4J5Ue4jd5pN/egKGR6iagvaY h+m2JV0rnXXrSPIw3U+TDBZivJ2v6f9rhlIs4KFdTXI0H0KU2XP9CZe0YaJT7Fts/be0rFXWO mlL3qJewwlBydy9C8/R6zFRg3OYt/hK4GvHUaP4UMO9B76YPNb028Gc6iJrAu3GvUhDhrgqxd OT54HTfwxKmPY3L4X8UL48dMDiACrMhMEL3/EGBEAYHBasN3+KqEzZ/G3UlbnZCrXD4s7f6jp F3Y9GeGLF1qBHw= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/18/22 10:16, Gerd Hoffmann wrote: > On Tue, Jan 18, 2022 at 09:20:43AM +0100, Helge Deller wrote: >> On 1/18/22 07:29, Gerd Hoffmann wrote: >>>> Please correct me if I'm wrong, but text-console emulation/scrolling = on DRM is >>>> currently unaccelerated and bound to Truecolour modes only, >>> >>> Yes. Adding support for formats beside argb8888 to the drm fbcon >>> emulation shouldn't be that much of a problem though. >> >> Really? Assuming a graphic card which runs with only 256 colors framebu= ffer >> is easily supported by DRM, and you can use fbcon without using lots of= memcpy()? > > Driver: programming a fixed color cube palette, then use RGB332. > > fbcon/fbdev emulation: RGB332 support must be added I think. But both > argb888 and rgb565 are supported today, so it should not be hard to find > the places where you have to add some code to handle RGB332 too. I'd expect that that framework is provided by DRM developers if there is t= he wish to get rid of old fbdev and transition existing drivers over to use DRM. >>> Acceleration is harder. The scroll acceleration had issues nobody >>> addressed for years, and on modern hardware it is simply not used, whi= ch >>> is probably the reason nobody stepped up fixing things and it ended up >>> being dropped. >> >> The DRM layer doesn't use scroll acceleration. >> More than 30 other existing fbdev drivers use it. > > Yes. The world shifted from 2d acceleration to 3d acceleration. Modern > hardware simply has no classic blitter any more. Which is a problem > when it comes to keeping scroll acceleration alive, it is already a very > niche use case and it will only become worse ... For me it's Ok that the DRM drivers don't use 2d acceleration (as it is to= day with the arguments mentioned multiple times). But the patches broke existing fbdev acceleration which is available by the fbdev drivers. That's a big regression from point of fbdev. >>> Bringing it back is much more work than just reverting the commits rem= oving it. >> >> Reverting those commits have no effect on DRM's usage of fbcon. >> But reverting those commits bring back scroll acceleration for all othe= rs. >> I'm trying to find out which patches did apparently fixed such issues >> for the REDRAW case. If you have a pointer it would be helpful. > > IIRC the code had a bunch of races and syzkaller flagged problems. > I didn't follow very closely though. That's sad. Nevertheless I wonder if the changes which were apparently done for the SCROLL_REDRAW case (on the higher level?) didn't also fixed the issues for SCROLL_MOVE. Helge