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=-1.0 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 C20C4C43387 for ; Fri, 21 Dec 2018 09:56:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9BEA32176F for ; Fri, 21 Dec 2018 09:56:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389016AbeLUJ4D (ORCPT ); Fri, 21 Dec 2018 04:56:03 -0500 Received: from mail.netline.ch ([148.251.143.178]:57959 "EHLO netline-mail3.netline.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387523AbeLUJ4D (ORCPT ); Fri, 21 Dec 2018 04:56:03 -0500 Received: from localhost (localhost [127.0.0.1]) by netline-mail3.netline.ch (Postfix) with ESMTP id 445862A6057; Fri, 21 Dec 2018 10:56:00 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at netline-mail3.netline.ch Received: from netline-mail3.netline.ch ([127.0.0.1]) by localhost (netline-mail3.netline.ch [127.0.0.1]) (amavisd-new, port 10024) with LMTP id MqFyEuBgndZT; Fri, 21 Dec 2018 10:55:59 +0100 (CET) Received: from thor (39.1.199.178.dynamic.wline.res.cust.swisscom.ch [178.199.1.39]) by netline-mail3.netline.ch (Postfix) with ESMTPSA id 5CA502A6055; Fri, 21 Dec 2018 10:55:59 +0100 (CET) Received: from localhost ([::1]) by thor with esmtp (Exim 4.91) (envelope-from ) id 1gaHXD-0001mW-3L; Fri, 21 Dec 2018 10:55:59 +0100 Subject: Re: [PATCH] drm: add capability DRM_CAP_ASYNC_UPDATE To: "Kazlauskas, Nicholas" , Daniel Vetter , Alex Deucher Cc: "dnicoara@chromium.org" , =?UTF-8?Q?St=c3=a9phane_Marchesin?= , Sean Paul , Alexandros Frantzis , David Airlie , Linux Kernel Mailing List , dri-devel , Tomasz Figa , Gustavo Padovan , Helen Koike , "kernel@collabora.com" References: <20181123215326.14274-1-helen.koike@collabora.com> <20181127133418.GT9144@intel.com> <6aa39654-6949-88b3-b949-b338d915ffd2@collabora.com> <0a0a35bf-69e4-8dcd-46fc-7053081480d5@collabora.com> <0bbee54e-7666-3d83-c80a-8ed2b4cc737d@amd.com> From: =?UTF-8?Q?Michel_D=c3=a4nzer?= Openpgp: preference=signencrypt Autocrypt: addr=michel@daenzer.net; prefer-encrypt=mutual; keydata= mQGiBDsehS8RBACbsIQEX31aYSIuEKxEnEX82ezMR8z3LG8ktv1KjyNErUX9Pt7AUC7W3W0b LUhu8Le8S2va6hi7GfSAifl0ih3k6Bv1Itzgnd+7ZmSrvCN8yGJaHNQfAevAuEboIb+MaVHo 9EMJj4ikOcRZCmQWw7evu/D9uQdtkCnRY9iJiAGxbwCguBHtpoGMxDOINCr5UU6qt+m4O+UD /355ohBBzzyh49lTj0kTFKr0Ozd20G2FbcqHgfFL1dc1MPyigej2gLga2osu2QY0ObvAGkOu WBi3LTY8Zs8uqFGDC4ZAwMPoFy3yzu3ne6T7d/68rJil0QcdQjzzHi6ekqHuhst4a+/+D23h Za8MJBEcdOhRhsaDVGAJSFEQB1qLBACOs0xN+XblejO35gsDSVVk8s+FUUw3TSWJBfZa3Imp V2U2tBO4qck+wqbHNfdnU/crrsHahjzBjvk8Up7VoY8oT+z03sal2vXEonS279xN2B92Tttr AgwosujguFO/7tvzymWC76rDEwue8TsADE11ErjwaBTs8ZXfnN/uAANgPLQjTWljaGVsIERh ZW56ZXIgPG1pY2hlbEBkYWVuemVyLm5ldD6IXgQTEQIAHgUCQFXxJgIbAwYLCQgHAwIDFQID AxYCAQIeAQIXgAAKCRBaga+OatuyAIrPAJ9ykonXI3oQcX83N2qzCEStLNW47gCeLWm/QiPY jqtGUnnSbyuTQfIySkK5AQ0EOx6FRRAEAJZkcvklPwJCgNiw37p0GShKmFGGqf/a3xZZEpjI qNxzshFRFneZze4f5LhzbX1/vIm5+ZXsEWympJfZzyCmYPw86QcFxyZflkAxHx9LeD+89Elx bw6wT0CcLvSv8ROfU1m8YhGbV6g2zWyLD0/naQGVb8e4FhVKGNY2EEbHgFBrAAMGA/0VktFO CxFBdzLQ17RCTwCJ3xpyP4qsLJH0yCoA26rH2zE2RzByhrTFTYZzbFEid3ddGiHOBEL+bO+2 GNtfiYKmbTkj1tMZJ8L6huKONaVrASFzLvZa2dlc2zja9ZSksKmge5BOTKWgbyepEc5qxSju YsYrX5xfLgTZC5abhhztpYhGBBgRAgAGBQI7HoVFAAoJEFqBr45q27IAlscAn2Ufk2d6/3p4 Cuyz/NX7KpL2dQ8WAJ9UD5JEakhfofed8PSqOM7jOO3LCA== Message-ID: <1c36151b-741f-0c25-2607-d36738937aba@daenzer.net> Date: Fri, 21 Dec 2018 10:55:58 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <0bbee54e-7666-3d83-c80a-8ed2b4cc737d@amd.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-12-20 6:38 p.m., Kazlauskas, Nicholas wrote: > On 12/20/18 12:09 PM, Daniel Vetter wrote: >> On Thu, Dec 20, 2018 at 6:03 PM Alex Deucher wrote: >>> On Thu, Dec 20, 2018 at 11:54 AM Daniel Vetter wrote: >>>> >>>> Not sure about the gamma thing since we had opposite bugs on i915 >>>> about gamma not being vsynced and tearing terribly. Cursor is special >>>> since it tends to be too small to notice tearing. >>> >>> Our cursor hw (and possibly gamma as well Nicholas? Harry?) is double >>> buffered, so we can update it any time for the most part and the >>> changes won't take affect until the next vupdate period. > > I haven't really investigated too much into the gamma stuttering issue, > but I think it's similar to the cursor update - a high volume of atomic > updates that ends up skipping over a vblank or two. FWIW, I don't think the use-cases described in https://bugs.freedesktop.org/108917 (Night Light / RedShift) involve a particularly high volume of gamma updates. I was able to reproduce the stuttering with ~10 gamma changes per second, but I suspect even a single one could cause a frame drop. I assume the issue is that gamma updates are done as separate atomic commits, which can delay other commits for page flips. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer