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=-0.9 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 1F2D7C46464 for ; Fri, 10 Aug 2018 17:19:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B22EB22448 for ; Fri, 10 Aug 2018 17:19:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="IeJVULrM"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="ar6sBxyM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B22EB22448 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728142AbeHJTuc (ORCPT ); Fri, 10 Aug 2018 15:50:32 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:42548 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727408AbeHJTuc (ORCPT ); Fri, 10 Aug 2018 15:50:32 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 0F3AA600C1; Fri, 10 Aug 2018 17:19:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1533921587; bh=akcOJVZGi1ZrmE+cxEg9c6fdi7upunOnanseKrBsi2g=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=IeJVULrMemvdDi3kHvvCffhMmsy87pIFHTqAPM63bmdURxgWLIFN0Oj78XMPKRLeh Bavv1HaToNPnZCOS146J0prMCzNy1VDKJ+l/1Qu1tvTmevo0UK8lY4zWxI5Pj8kFtp 4g0HcFx7QaIeRSi2EPkBgFaDr0VWRto8IOsOR8Ww= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id D7C29600C1; Fri, 10 Aug 2018 17:19:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1533921585; bh=akcOJVZGi1ZrmE+cxEg9c6fdi7upunOnanseKrBsi2g=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ar6sBxyMHyobgwV1XFFHbg32fK5xqBuxZ3uWTZ4U0ZpyQFSQQCmUXTf8gFX1Dpyae dzM+xOLWdIromcCWLXC8gGBQNfRVrvz4L1oiz4Kg3gbv/flS2RsO2Pw9Dzn1/wghWA E4qUn3xEBdks5svATMgzgZf5Sf42QH8maOabHUto= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 10 Aug 2018 10:19:45 -0700 From: Sodagudi Prasad To: "Rafael J. Wysocki" Cc: Rishabh Bhatnagar , Greg Kroah-Hartman , tsoni@codeaurora.org, Vikram Mulukutla , Linux Kernel Mailing List , ckadabi@codeaurora.org, rjwysocki@gmail.com Subject: Re: [PATCH] dd: Invoke one probe retry cycle after every initcall level In-Reply-To: References: <1532035440-7860-1-git-send-email-rishabhb@codeaurora.org> <68b90830d5024ce75a20b017aaf21c05@codeaurora.org> <2aecb7753a305aac081c9c9b981cedc1@codeaurora.org> Message-ID: <1b41135c952258102754a0eab876a77b@codeaurora.org> X-Sender: psodagud@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-08-10 00:10, Rafael J. Wysocki wrote: > On Fri, Aug 10, 2018 at 12:30 AM, wrote: >> On 2018-08-06 01:53, Rafael J. Wysocki wrote: >>> >>> On Fri, Aug 3, 2018 at 12:20 AM, Sodagudi Prasad >>> wrote: >>>>> >>>>> From: RAFAEL J. WYSOCKI >>>>> Date: Wed, Aug 1, 2018 at 2:21 PM >>>>> Subject: Re: [PATCH] dd: Invoke one probe retry cycle after every >>>>> initcall level >>>>> To: Rishabh Bhatnagar >>>>> Cc: "Rafael J. Wysocki" , Greg Kroah-Hartman >>>>> , Linux Kernel Mailing List >>>>> , ckadabi@codeaurora.org, >>>>> tsoni@codeaurora.org, Vikram Mulukutla >>>>> >>>>> >>>>> On Wed, Aug 1, 2018 at 11:18 PM, wrote: >>>>>> >>>>>> >>>>>> On 2018-07-24 01:24, Rafael J. Wysocki wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Mon, Jul 23, 2018 at 10:22 PM, >>>>>>> wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On 2018-07-23 04:17, Rafael J. Wysocki wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Thu, Jul 19, 2018 at 11:24 PM, Rishabh Bhatnagar >>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Drivers that are registered at an initcall level may have to >>>>>>>>>> wait until late_init before the probe deferral mechanism can >>>>>>>>>> retry their probe functions. It is possible that their >>>>>>>>>> dependencies were resolved much earlier, in some cases even >>>>>>>>>> before the next initcall level. Invoke one probe retry cycle >>>>>>>>>> at every _sync initcall level, allowing these drivers to be >>>>>>>>>> probed earlier. >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Can you please say something about the actual use case this is >>>>>>>>> expected to address? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> We have a display driver that depends 3 other devices to be >>>>>>>> probed so that it can bring-up the display. Because of >>>>> >>>>> >>>>> dependencies >>>>>>>> >>>>>>>> >>>>>>>> not being met the deferral mechanism defers the probes for a >>>>>>>> later >>>>> >>>>> >>>>> time, >>>>>>>> >>>>>>>> >>>>>>>> even though the dependencies might be met earlier. With this >>>>> >>>>> >>>>> change >>>>>>>> >>>>>>>> >>>>>>>> display can be brought up much earlier. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> OK >>>>>>> >>>>>>> What runlevel brings up the display after the change? >>>>>>> >>>>>>> Thanks, >>>>>>> Rafael >>>>>> >>>>>> >>>>>> After the change the display can come up after device_initcall >>>>>> level >>>>>> itself. >>>>>> The above mentioned 3 devices are probed at 0.503253, 0.505210 and >>>>> >>>>> >>>>> 0.523264 >>>>>> >>>>>> >>>>>> secs. >>>>>> Only the first device is probed successfully. With the current >>>>>> deferral mechanism the devices get probed again after >>>>>> late_initcall >>>>>> at 9.19 and 9.35 secs. So display can only come up after 9.35 >>>>>> secs. >>>>>> With this change the devices are re-probed successfully at 0.60 >>>>>> and >>>>>> 0.613 secs. Therefore display can come just after 0.613 secs. >>>>> >>>>> >>>>> >>>>> OK, so why do you touch the initcall levels earlier than device_? >>>> >>>> >>>> 1) re-probe probing devices in the active list on every level >>>> help >>>> to >>>> avoid circular dependency pending list. >>>> 2) There are so many devices which gets deferred in earlier >>>> init >>>> call >>>> levels, so we wanted to reprobe them at every successive init call >>>> level. >>> >>> >>> Do you have specific examples of devices for which that helps? >>> >>>>> >>>>>> This change helps in overall android bootup as well. >>>>> >>>>> >>>>> >>>>> How exactly? >>>> >>>> >>>> We have seen less no of re-probes at late_init and most of the >>>> driver's >>>> dependency met earlier than late_init call level. It helped display >>>> and >>>> couple of other drivers by executing the re probe work at every init >>>> level. >>> >>> >>> So I can believe that walking the deferred list on device_initcall >>> and >>> maybe on device_initcall_sync may help, but I'm not quite convinced >>> that it matters for the earlier initcall levels. >> >> >> Many of our drivers are dependent on the regulator and bus driver. >> Both the regulator and bus driver are probed in the subsys_initcall >> level. >> Now the probe of bus driver requires regulator to be working. If the >> probe >> of >> bus driver happens before regulator, then bus driver's probe will be >> deferred and all other device's probes which depend on bus driver will >> also >> be deferred. >> The impact of this problem is reduced if we have this patch. > > Fair enough, but this information should be there in the changelog of > your patch. > > And why do you do that for arch_initcall_sync()? You are right and we can remove arch_initcall_sync(). Added some logging and observed that, none of the devices are re-probed in the arch_initcall_sync level. -Thanks, Prasad -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, Linux Foundation Collaborative Project