From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frank Rowand Subject: Re: [GIT PULL] On-demand device probing Date: Wed, 21 Oct 2015 11:18:08 -0700 Message-ID: <5627D6E0.5020708@gmail.com> 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> Reply-To: frowand.list@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20151021162758.GP32054@sirena.org.uk> Sender: linux-i2c-owner@vger.kernel.org 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 List-Id: linux-gpio@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: >=20 >>> To be clear, I was saying that this series should NOT affect total >>> boot times much. >=20 >> 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 lon= ger >> than expected to be ready during boot (St=E9phane Marchesin repor= ted 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. >=20 > 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 th= ose > 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? >=20 >> 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? >=20 > See above, my understanding was that the performance improvements wer= e > more around improved control/predictability/handwave of the boot > ordering rather than total time. >=20