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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 27E40C48BE8 for ; Tue, 15 Jun 2021 09:46:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 111E361441 for ; Tue, 15 Jun 2021 09:46:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231220AbhFOJsZ (ORCPT ); Tue, 15 Jun 2021 05:48:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230519AbhFOJsZ (ORCPT ); Tue, 15 Jun 2021 05:48:25 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECEC2C061574 for ; Tue, 15 Jun 2021 02:46:20 -0700 (PDT) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id D9DFA436; Tue, 15 Jun 2021 11:46:16 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1623750377; bh=owyRg9BfLHSyUAfAxBSUYA0KZUQrktezYcb7gHSkics=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=e8W03Key7HN+OcFEZ7uQCvRvZcaevfZtNuhmfBiRGix5juc2h9DF1pIaA+thOwZOV HawGX/s+C9z9U97esgDFbnpiPq2yXz2nmFgqrLgUqTPC8GxXKltK2x9MoTTSSP7LqT huY3Wnd5+Xd7C9cOjwDe+mAPV2NfxR9N+qSbHSY4= Date: Tue, 15 Jun 2021 12:45:57 +0300 From: Laurent Pinchart To: Simon Ser Cc: Pekka Paalanen , Liviu Dudau , Haneen Mohammed , Alexandre Belloni , Linux Doc Mailing List , Xinliang Liu , Daniel Vetter , Edmund Dea , Alexandre Torgue , dri-devel , Russell King , Melissa Wen , Tomi Valkeinen , Thierry Reding , Benjamin Gaignard , Anitha Chrisanthus , Daniel Vetter , Steven Price , Sam Ravnborg , Jyri Sarha , Jerome Brunet , Marek Vasut , Joonyoung Shim , Qiang Yu , Krzysztof Kozlowski , Kevin Hilman , Neil Armstrong , Alyssa Rosenzweig , Xinwei Kong , Jonathan Hunter , David Airlie , Ludovic Desroches , Kieran Bingham , VMware Graphics , NXP Linux Team , Ben Skeggs , Chun-Kuang Hu , Maxime Coquelin , Jonas Karlman , Martin Blumenstingl , Chen Feng , Sascha Hauer , Alison Wang , Roland Scheidegger , Andrzej Hajda , Hans de Goede , Maxime Ripard , Rodrigo Vivi , Matthias Brugger , Nicolas Ferre , Chen-Yu Tsai , Sean Paul , Thomas Zimmermann , Paul Cercueil , Jernej Skrabec , Rodrigo Siqueira , Hyun Kwon , Boris Brezillon , Andrew Jeffery , Huang Rui , Yannick Fertr e , Jonathan Corbet , Seung-Woo Kim , Sandy Huang , Robert Foss , Joel Stanley , Tomeu Vizoso , Kyungmin Park , Noralf =?utf-8?Q?Tr=C3=B8nnes?= , Philippe Cornu , Pengutronix Kernel Team , Alex Deucher , Tian Tao , Oleksandr Andrushchenko , Shawn Guo , Christian =?utf-8?B?S8O2bmln?= , Gerd Hoffmann Subject: Re: [PATCH v3] Documentation: gpu: Mention the requirements for new properties Message-ID: References: <20210610174731.1209188-1-maxime@cerno.tech> <20210611120309.2b5eb4htupv5ss32@e110455-lin.cambridge.arm.com> <20210614174912.15a49336@eldfell> <20210614152413.nguqia3s4tlowio4@e110455-lin.cambridge.arm.com> <20210615100335.0b8f96d5@eldfell> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tue, Jun 15, 2021 at 07:15:18AM +0000, Simon Ser wrote: > On Tuesday, June 15th, 2021 at 09:03, Pekka Paalanen wrote: > > > indeed it will, but what else could one do to test userspace KMS > > clients in generic CI where all you can have is virtual hardware? Maybe > > in the long run VKMS needs to loop back to a userspace daemon that > > implements all the complex processing and returns the writeback result > > via VKMS again? That daemon would then need a single upstream, like the > > kernel, where it is maintained and correctness verified. > > The complex processing must be implemented even without write-back, because > user-space can ask for CRCs of the CRTC. > > > Or an LD_PRELOAD that hijacks all KMS ioctls and implements virtual > > stuff in userspace? Didn't someone already have something like that? > > It would need to be lifted to be a required part of kernel UAPI > > submissions, I suppose like IGT is nowadays. > > FWIW, I have a mock libdrm [1] for libliftoff. This is nowhere near a full > software implementation with write-back connectors, but allows to expose > virtual planes and check atomic commits in CI. > > [1]: https://github.com/emersion/libliftoff/blob/master/test/libdrm_mock.c > > > For compositor developers like me knowing the exact formulas would be a huge > > benefit as it would allow me to use KMS to off-load precision-sensitive > > operations (e.g. professional color management). Otherwise, compositors > > probably need a switch: "high quality color management? Then do not use KMS > > features." > > I think for alpha blending there are already rounding issues depending on the > hardware. I wouldn't keep my hopes up for any guarantee that all hw uses the > exact same formulae for color management stuff. Good, because otherwise you would be very quickly disappointed :-) For scaling we would also need to replicate the exact same filter taps, which are often not documented. -- Regards, Laurent Pinchart