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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 207B5C46466 for ; Sat, 3 Oct 2020 00:14:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB4E6206F8 for ; Sat, 3 Oct 2020 00:14:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="bc+Deoda" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725536AbgJCAOX (ORCPT ); Fri, 2 Oct 2020 20:14:23 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:47802 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725379AbgJCAOX (ORCPT ); Fri, 2 Oct 2020 20:14:23 -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 DE87A2A2; Sat, 3 Oct 2020 02:14:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1601684060; bh=+6oLaNXCzW10EOi7yZGKf53UByBP3OfCZ2DbymvFru4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bc+Deodasn0sCNZhaf6Gx6XbXjbyA7lfRaoFjKOxRjIEndIeT2xnvZAokcMbefTQw OP9+oMRViNvXrrED+cG2VM92CfLmCZbm2aFhZAD3Wyigb0P4dwUvUhDrhDIY7727CE Y+hgqcbTo6LIJe9vjNIbPBBkIdeb+0UBK1ua8qu0= Date: Sat, 3 Oct 2020 03:13:42 +0300 From: Laurent Pinchart To: Saravana Kannan Cc: Grygorii Strashko , Rob Herring , Frank Rowand , Geert Uytterhoeven , Greg Kroah-Hartman , linux-omap , "open list:THERMAL" , Peter Ujfalusi , "Rafael J. Wysocki" , Tomi Valkeinen , Tony Lindgren , Ulf Hansson , Android Kernel Team , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v1] of: platform: Batch fwnode parsing in the init_machine() path Message-ID: <20201003001342.GA1730@pendragon.ideasonboard.com> References: <20201001225952.3676755-1-saravanak@google.com> <20201002175423.GE3933@pendragon.ideasonboard.com> <20201002182712.GF3933@pendragon.ideasonboard.com> <11018e7e-a6a1-2df6-5639-821a7c0cb68b@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org Hi Saravana, On Fri, Oct 02, 2020 at 12:56:30PM -0700, Saravana Kannan wrote: > On Fri, Oct 2, 2020 at 11:35 AM 'Grygorii Strashko' via kernel-team wrote: > > On 02/10/2020 21:27, Laurent Pinchart wrote: > > > On Fri, Oct 02, 2020 at 10:58:55AM -0700, Saravana Kannan wrote: > > >> On Fri, Oct 2, 2020 at 10:55 AM Laurent Pinchart wrote: > > >>> On Fri, Oct 02, 2020 at 10:51:51AM -0700, Saravana Kannan wrote: > > >>>> On Fri, Oct 2, 2020 at 7:08 AM Rob Herring wrote: > > >>>>> On Thu, Oct 1, 2020 at 5:59 PM Saravana Kannan wrote: > > >>>>>> > > >>>>>> When commit 93d2e4322aa7 ("of: platform: Batch fwnode parsing when > > >>>>>> adding all top level devices") optimized the fwnode parsing when all top > > >>>>>> level devices are added, it missed out optimizing this for platform > > >>>>>> where the top level devices are added through the init_machine() path. > > >>>>>> > > >>>>>> This commit does the optimization for all paths by simply moving the > > >>>>>> fw_devlink_pause/resume() inside of_platform_default_populate(). > > >>>>>> > > >>>>>> Reported-by: Tomi Valkeinen > > >>>>>> Signed-off-by: Saravana Kannan > > >>>>>> --- > > >>>>>> drivers/of/platform.c | 19 +++++++++++++++---- > > >>>>>> 1 file changed, 15 insertions(+), 4 deletions(-) > > >>>>>> > > >>>>>> diff --git a/drivers/of/platform.c b/drivers/of/platform.c > > >>>>>> index 071f04da32c8..79972e49b539 100644 > > >>>>>> --- a/drivers/of/platform.c > > >>>>>> +++ b/drivers/of/platform.c > > >>>>>> @@ -501,8 +501,21 @@ int of_platform_default_populate(struct device_node *root, > > >>>>>> const struct of_dev_auxdata *lookup, > > >>>>>> struct device *parent) > > >>>>>> { > > >>>>>> - return of_platform_populate(root, of_default_bus_match_table, lookup, > > >>>>>> - parent); > > >>>>>> + int ret; > > >>>>>> + > > >>>>>> + /* > > >>>>>> + * fw_devlink_pause/resume() are only safe to be called around top > > >>>>>> + * level device addition due to locking constraints. > > >>>>>> + */ > > >>>>>> + if (!root) > > >>>>>> + fw_devlink_pause(); > > >>>>>> + > > >>>>>> + ret = of_platform_populate(root, of_default_bus_match_table, lookup, > > >>>>>> + parent); > > >>>>> > > >>>>> of_platform_default_populate() vs. of_platform_populate() is just a > > >>>>> different match table. I don't think the behavior should otherwise be > > >>>>> different. > > >>>>> > > >>>>> There's also of_platform_probe() which has slightly different matching > > >>>>> behavior. It should not behave differently either with respect to > > >>>>> devlinks. > > >>>> > > >>>> So I'm trying to do this only when the top level devices are added for > > >>>> the first time. of_platform_default_populate() seems to be the most > > >>>> common path. For other cases, I think we just need to call > > >>>> fw_devlink_pause/resume() wherever the top level devices are added for > > >>>> the first time. As I said in the other email, we can't add > > >>>> fw_devlink_pause/resume() by default to of_platform_populate(). > > >>>> > > >>>> Do you have other ideas for achieving "call fw_devlink_pause/resume() > > >>>> only when top level devices are added for the first time"? > > >>> > > >>> I'm not an expert in this domain, but before investigating it, would you > > >>> be able to share a hack patch that implements this (in the most simple > > >>> way) to check if it actually fixes the delays I experience on my system > > >>> ? > > >> > > >> So I take it the patch I sent out didn't work for you? Can you tell me > > >> what machine/DT you are using? > > > > > > I've replied to the patch: > > > > > > Based on v5.9-rc5, before the patch: > > > > > > [ 0.652887] cpuidle: using governor menu > > > [ 12.349476] No ATAGs? > > > > > > After the patch: > > > > > > [ 0.650460] cpuidle: using governor menu > > > [ 12.262101] No ATAGs? > > > > > > I'm using an AM57xx EVM, whose DT is not upstream, but it's essentially > > > a am57xx-beagle-x15-revb1.dts (it includes that DTS) with a few > > > additional nodes for GPIO keys, LCD panel, backlight and touchscreen. > > > > > > > hope you are receiving my mails as I've provided you with all required information already [1] > > Laurent/Grygorii, > > Looks like I'm definitely missing emails. Sorry about the confusion. > > I have some other urgent things on my plate right now. Is it okay if I > get to this in a day or two? In the end, we'll find a solution that > addresses most/all of the delay. No issue on my side. By the way, during initial investigations, I've traced code paths to figure out if there was a particular step that would consume a large amount of time, and found out that of_platform_populate() ends up executing devlink-related code that seems to have an O(n^3) complexity on the number of devices, with a few dozens of milliseconds for each iteration. That's a very bad complexity. -- Regards, Laurent Pinchart