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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 AB01CC433DF for ; Wed, 8 Jul 2020 14:22:51 +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 85D0F206E9 for ; Wed, 8 Jul 2020 14:22:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 85D0F206E9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de 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 011496E1A8; Wed, 8 Jul 2020 14:22:51 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 49AC26E1A8 for ; Wed, 8 Jul 2020 14:22:49 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 53532AC40; Wed, 8 Jul 2020 14:22:48 +0000 (UTC) Subject: Re: drm/ast something ate high-res modes (5.3->5.6 regression) To: =?UTF-8?Q?Ilpo_J=c3=a4rvinen?= References: From: Thomas Zimmermann Message-ID: <930a059f-ce19-f479-3345-0bc8c3d27518@suse.de> Date: Wed, 8 Jul 2020 16:22:43 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: 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: dri-devel@lists.freedesktop.org Content-Type: multipart/mixed; boundary="===============0539028131==" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --===============0539028131== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="G1EXzPBh3ucQm1Elpa5bVWSy8K9VswbVv" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --G1EXzPBh3ucQm1Elpa5bVWSy8K9VswbVv Content-Type: multipart/mixed; boundary="6GMExq5x08fbguz4hZV69QJ6GqXXAmuod"; protected-headers="v1" From: Thomas Zimmermann To: =?UTF-8?Q?Ilpo_J=c3=a4rvinen?= Cc: dri-devel@lists.freedesktop.org Message-ID: <930a059f-ce19-f479-3345-0bc8c3d27518@suse.de> Subject: Re: drm/ast something ate high-res modes (5.3->5.6 regression) References: In-Reply-To: --6GMExq5x08fbguz4hZV69QJ6GqXXAmuod Content-Type: text/plain; charset=iso-8859-15 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Am 08.07.20 um 15:46 schrieb Ilpo J=E4rvinen: > On Wed, 8 Jul 2020, Thomas Zimmermann wrote: >=20 >> Hi >> >> Am 08.07.20 um 12:05 schrieb Ilpo J=E4rvinen: >>> Hi, >>> >>> After upgrading kernel from 5.3 series to 5.6.16 something seems to=20 >>> prevent me from achieving high resolutions with the ast driver. >> >> Thanks for reporting. It's not a bug, but a side effect of atomic >> modesetting. >> >> During pageflips, the old code used to kick out the currently displaye= d >> framebuffer and then load in the new one. If that failed, the display >> went garbage. >> >> In v5.6-rc1, we merged atomic modesetting for ast. This means that >> screen updates are more reliable, but we have to over-commit resources= =2E >> Specifically, we have to reserve space for two buffers in video memory= >> while a pageflip happens. 1920x1200@32 are ~9MiB of framebuffer memory= =2E >> If your device has 16 MiB of VRAM, there's no space left for the secon= d >> framebuffer. Hence, the resolution is no longer supported. >> >> On the positive side, you can now use Wayland compositors with ast. >> Atomic modesetting adds the necessary interfaces. >=20 > Ok, thanks for the info although it's quite disappointing (not the firs= t=20 > time to lose features with kms, migrating to it made me to lose dpms) ;= -). >=20 > As it's quite annoying to lose a high resolution mode (or be stuck in=20 > some old kernel), would it be technically feasible to make the framebuf= fer=20 > allocation asymmetrical? That is, the switch to high-res mode would get= > rejected when it would be into the smaller of the two buffers but not w= hen=20 > the arrangement is the other way around? I'm not sure what you mean here, but generally, there's no way of fixing this without performance penalty. The screen resolution is only programmed once. Later updates only require pageflips. For each pageflip, atomic modesetting requires the new and the old framebuffer in video memory at the same time. These two framebuffers are typically allocated once by Gnome/KDE/etc compositors, and compositors go back and forth between them. It's basically double buffering. Best regards Thomas >=20 >=20 --=20 Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 N=FCrnberg, Germany (HRB 36809, AG N=FCrnberg) Gesch=E4ftsf=FChrer: Felix Imend=F6rffer --6GMExq5x08fbguz4hZV69QJ6GqXXAmuod-- --G1EXzPBh3ucQm1Elpa5bVWSy8K9VswbVv Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQFIBAEBCAAyFiEEchf7rIzpz2NEoWjlaA3BHVMLeiMFAl8F1rQUHHR6aW1tZXJt YW5uQHN1c2UuZGUACgkQaA3BHVMLeiPWfgf+IzVz44AEIAgiXKbIoIMO7tnV4ywu 85qTtv/c1IT3PxWXadlGmTOGbZQadbQA1J4xcwp9m/0WFR9o6+nmqN3AysZwjGB3 YVWocioi7iKDGhI20EX200NA+WzXUQou9DE5spgzD1nUIRymPkSTY3rhiln0cfOW yvS9IkZyrNq/zzAweVdDulxBn74ZmyH7zTETMvMyxWI/7Oo2wcrAs/vMuYnsJPg5 9EVLRuywHvUFVrV86jfqxpEJAwNY1VyXqgAx7Va03VVHfEErzW3b8ksPEbruiBu2 qRCS/mIAkxA119X10DLUI5gZS/FjFyn6iaU91FYQO15hX6jT4IGuS5zxCg== =vhX3 -----END PGP SIGNATURE----- --G1EXzPBh3ucQm1Elpa5bVWSy8K9VswbVv-- --===============0539028131== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel --===============0539028131==--