From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755337AbbJUSSR (ORCPT ); Wed, 21 Oct 2015 14:18:17 -0400 Received: from mail-pa0-f66.google.com ([209.85.220.66]:33379 "EHLO mail-pa0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752747AbbJUSSL (ORCPT ); Wed, 21 Oct 2015 14:18:11 -0400 Message-ID: <5627D6E0.5020708@gmail.com> Date: Wed, 21 Oct 2015 11:18:08 -0700 From: Frank Rowand Reply-To: frowand.list@gmail.com User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Mark Brown CC: Tomeu Vizoso , Greg Kroah-Hartman , Rob Herring , Russell King , Michael Turquette , Stephen Boyd , Vinod Koul , Dan Williams , Linus Walleij , Alexandre Courbot , Thierry Reding , David Airlie , =?ISO-8859-1?Q?Terje_Bergstr=F6m?= , Stephen Warren , Wolfram Sang , Grant Likely , Kishon Vijay Abraham I , Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse , Liam Girdwood , Felipe Balbi , Jingoo Han , Lee Jones , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , "linux-kernel@vger.kernel.org" , linux-clk@vger.kernel.org, dmaengine@vger.kernel.org, linux-gpio@vger.kernel.org, "dri-devel@lists.freedesktop.org" , "linux-tegra@vger.kernel.org" , linux-i2c@vger.kernel.org, "devicetree@vger.kernel.org" , "linux-pm@vger.kernel.org" , Linux PWM List , "linux-usb@vger.kernel.org" , linux-fbdev@vger.kernel.org Subject: Re: [GIT PULL] On-demand device probing References: <561E1378.6000906@collabora.com> <20151017065750.GA18607@kroah.com> <20151018192931.GY14956@sirena.org.uk> <20151018193757.GA9147@kroah.com> <20151018195330.GB14956@sirena.org.uk> <5627B677.5090109@gmail.com> <20151021162758.GP32054@sirena.org.uk> In-Reply-To: <20151021162758.GP32054@sirena.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/21/2015 9:27 AM, Mark Brown wrote: > On Wed, Oct 21, 2015 at 08:59:51AM -0700, Frank Rowand wrote: >> On 10/19/2015 5:34 AM, Tomeu Vizoso wrote: > >>> To be clear, I was saying that this series should NOT affect total >>> boot times much. > >> I'm confused. If I understood correctly, improving boot time was >> the key justification for accepting this patch set. For example, >> from "[PATCH v7 0/20] On-demand device probing": >> >> I have a problem with the panel on my Tegra Chromebook taking longer >> than expected to be ready during boot (Stéphane Marchesin reported what >> is basically the same issue in [0]), and have looked into ordered >> probing as a better way of solving this than moving nodes around in the >> DT or playing with initcall levels and linking order. >> >> ... >> >> With this series I get the kernel to output to the panel in 0.5s, >> instead of 2.8s. > > Overall boot time and time to get some individual built in component up > and running aren't the same thing - what this'll do is get things up > more in the link order of the leaf consumers rather than deferring those > leaf consumers when their dependencies aren't ready yet. Thanks! I read too much into what was being improved. So this patch series, which on other merits may be a good idea, is as a by product solving a specific ordering issue, moving successful panel initialization to an earlier point in the boot sequence, if I now understand more correctly. In that context, this seems like yet another ad hoc way of causing the probe order to change in a way to solves one specific issue? Could it just as likely move the boot order of some other driver on some other board later, to the detriment of somebody else? > >> While not as dramatic as your results, they are somewhat supportive. >> What has changed your assessment that the on-demand device probing >> patches will give a big boot performance increase? Do you have >> new data or analysis? > > See above, my understanding was that the performance improvements were > more around improved control/predictability/handwave of the boot > ordering rather than total time. >