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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 04C79C04FF3 for ; Mon, 24 May 2021 04:04:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3919611CE for ; Mon, 24 May 2021 04:04:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229908AbhEXEGR (ORCPT ); Mon, 24 May 2021 00:06:17 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:54896 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229562AbhEXEGQ (ORCPT ); Mon, 24 May 2021 00:06:16 -0400 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id EB704476; Mon, 24 May 2021 06:04:46 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1621829087; bh=CrvWH+KyOQeB9DmufrADhchqE4gnpWjYgd9o5q0l/RU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=N+7rOFQ54/PFo0avzSIGZTK6fqy3XN9Aci5iWuHDeW8Es50uFzgefXdx9glIREuPs TK+KvrVMbid16SpJdXTfgmENiJ9+QrcY1SGuVdktuaD9F+Zn/VBiKg0J9txWJaEfuq m15H9F4jEY+dL493Py3fEXw/71EhVn2c09P4aPv4= Date: Mon, 24 May 2021 07:04:43 +0300 From: Laurent Pinchart To: Maxime Ripard Cc: dri-devel@lists.freedesktop.org, Daniel Vetter , David Airlie , Maarten Lankhorst , Thomas Zimmermann , linux-doc@vger.kernel.org, Jonathan Corbet , Alexandre Belloni , Alexandre Torgue , Alex Deucher , Alison Wang , Alyssa Rosenzweig , Andrew Jeffery , Andrzej Hajda , Anitha Chrisanthus , Benjamin Gaignard , Ben Skeggs , Boris Brezillon , Brian Starkey , Chen Feng , Chen-Yu Tsai , Christian Gmeiner , Christian =?utf-8?B?S8O2bmln?= , Chun-Kuang Hu , Edmund Dea , Eric Anholt , Fabio Estevam , Gerd Hoffmann , Haneen Mohammed , Hans de Goede , Heiko =?utf-8?Q?St=C3=BCbner?= , Huang Rui , Hyun Kwon , Inki Dae , Jani Nikula , Jernej Skrabec , Jerome Brunet , Joel Stanley , John Stultz , Jonas Karlman , Jonathan Hunter , Joonas Lahtinen , Joonyoung Shim , Jyri Sarha , Kevin Hilman , Kieran Bingham , Krzysztof Kozlowski , Kyungmin Park , Linus Walleij , Liviu Dudau , Lucas Stach , Ludovic Desroches , Marek Vasut , Martin Blumenstingl , Matthias Brugger , Maxime Coquelin , Maxime Ripard , Melissa Wen , Neil Armstrong , Nicolas Ferre , Noralf =?utf-8?Q?Tr=C3=B8nnes?= , NXP Linux Team , Oleksandr Andrushchenko , Patrik Jakobsson , Paul Cercueil , Pengutronix Kernel Team , Philippe Cornu , Philipp Zabel , Qiang Yu , Rob Clark , Robert Foss , Rob Herring , Rodrigo Siqueira , Rodrigo Vivi , Roland Scheidegger , Russell King , Sam Ravnborg , Sandy Huang , Sascha Hauer , Sean Paul , Seung-Woo Kim , Shawn Guo , Stefan Agner , Steven Price , Sumit Semwal , Thierry Reding , Tian Tao , Tomeu Vizoso , Tomi Valkeinen , VMware Graphics , Xinliang Liu , Xinwei Kong , Yannick Fertre , Zack Rusin , Daniel Vetter Subject: Re: [PATCH v2] Documentation: gpu: Mention the requirements for new properties Message-ID: References: <20210520142435.267873-1-maxime@cerno.tech> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210520142435.267873-1-maxime@cerno.tech> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Hi Maxime, Thank you for the patch. On Thu, May 20, 2021 at 04:24:35PM +0200, Maxime Ripard wrote: > New KMS properties come with a bunch of requirements to avoid each > driver from running their own, inconsistent, set of properties, > eventually leading to issues like property conflicts, inconsistencies > between drivers and semantics, etc. > > Let's document what we expect. > > Cc: Alexandre Belloni > Cc: Alexandre Torgue > Cc: Alex Deucher > Cc: Alison Wang > Cc: Alyssa Rosenzweig > Cc: Andrew Jeffery > Cc: Andrzej Hajda > Cc: Anitha Chrisanthus > Cc: Benjamin Gaignard > Cc: Ben Skeggs > Cc: Boris Brezillon > Cc: Brian Starkey > Cc: Chen Feng > Cc: Chen-Yu Tsai > Cc: Christian Gmeiner > Cc: "Christian König" > Cc: Chun-Kuang Hu > Cc: Edmund Dea > Cc: Eric Anholt > Cc: Fabio Estevam > Cc: Gerd Hoffmann > Cc: Haneen Mohammed > Cc: Hans de Goede > Cc: "Heiko Stübner" > Cc: Huang Rui > Cc: Hyun Kwon > Cc: Inki Dae > Cc: Jani Nikula > Cc: Jernej Skrabec > Cc: Jerome Brunet > Cc: Joel Stanley > Cc: John Stultz > Cc: Jonas Karlman > Cc: Jonathan Hunter > Cc: Joonas Lahtinen > Cc: Joonyoung Shim > Cc: Jyri Sarha > Cc: Kevin Hilman > Cc: Kieran Bingham > Cc: Krzysztof Kozlowski > Cc: Kyungmin Park > Cc: Laurent Pinchart > Cc: Linus Walleij > Cc: Liviu Dudau > Cc: Lucas Stach > Cc: Ludovic Desroches > Cc: Marek Vasut > Cc: Martin Blumenstingl > Cc: Matthias Brugger > Cc: Maxime Coquelin > Cc: Maxime Ripard > Cc: Melissa Wen > Cc: Neil Armstrong > Cc: Nicolas Ferre > Cc: "Noralf Trønnes" > Cc: NXP Linux Team > Cc: Oleksandr Andrushchenko > Cc: Patrik Jakobsson > Cc: Paul Cercueil > Cc: Pengutronix Kernel Team > Cc: Philippe Cornu > Cc: Philipp Zabel > Cc: Qiang Yu > Cc: Rob Clark > Cc: Robert Foss > Cc: Rob Herring > Cc: Rodrigo Siqueira > Cc: Rodrigo Vivi > Cc: Roland Scheidegger > Cc: Russell King > Cc: Sam Ravnborg > Cc: Sandy Huang > Cc: Sascha Hauer > Cc: Sean Paul > Cc: Seung-Woo Kim > Cc: Shawn Guo > Cc: Stefan Agner > Cc: Steven Price > Cc: Sumit Semwal > Cc: Thierry Reding > Cc: Tian Tao > Cc: Tomeu Vizoso > Cc: Tomi Valkeinen > Cc: VMware Graphics > Cc: Xinliang Liu > Cc: Xinwei Kong > Cc: Yannick Fertre > Cc: Zack Rusin > Reviewed-by: Daniel Vetter > Signed-off-by: Maxime Ripard > > --- > > Changes from v2: > - Typos and wording reported by Daniel and Alex > --- > Documentation/gpu/drm-kms.rst | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst > index 87e5023e3f55..c28b464dd397 100644 > --- a/Documentation/gpu/drm-kms.rst > +++ b/Documentation/gpu/drm-kms.rst > @@ -463,6 +463,25 @@ KMS Properties > This section of the documentation is primarily aimed at user-space developers. > For the driver APIs, see the other sections. > > +Requirements > +------------ > + > +KMS drivers might need to add extra properties to support new features. > +Each new property introduced in a driver need to meet a few s/need/needs/ > +requirements, in addition to the one mentioned above.: s/above./above/ > + > +- It must be standardized, with some documentation to describe how the > + property can be used. > + > +- It must provide a generic helper in the core code to register that > + property on the object it attaches to. > + > +- Its content must be decoded by the core and provided in the object's > + associated state structure. That includes anything drivers might want to > + precompute, like :c:type:`struct drm_clip_rect ` for planes. Does this effectively mean that we completely forbid driver-specific properties ? While I agree that we should strive for standardization, there are two issues that worry me. The first one is simple, we may need to control features that would be very device-specific, and standardizing properties doesn't seem to make much sense in that case. The second issue relates to properties that could be applicable to multiple devices, but for which we have a single driver. Designing a standard with a single data point usually leads to a bad design. I'm not sure how to handle this correctly though, as we certainly don't want this to be taken as an excuse to create driver-specific properties when generic properties would make sense. > +- An IGT test must be submitted where reasonable. > + > Property Types and Blob Property Support > ---------------------------------------- > -- Regards, Laurent Pinchart