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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT 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 2F9C2C31E45 for ; Tue, 11 Jun 2019 21:52:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED10F20874 for ; Tue, 11 Jun 2019 21:52:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="AVWVFnz3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436581AbfFKVwp (ORCPT ); Tue, 11 Jun 2019 17:52:45 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:34702 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407165AbfFKVwo (ORCPT ); Tue, 11 Jun 2019 17:52:44 -0400 Received: by mail-pl1-f195.google.com with SMTP id i2so5683902plt.1 for ; Tue, 11 Jun 2019 14:52:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=mSH6vjaD/nr1X2l9Lu5p2XVHT+RbgtF+8lv2TXUlGxI=; b=AVWVFnz3EkCZsE+NYatD/YXB62zlYFWeSCIzuEw4yezw8A74s/W8lvaK0EgK4htQ4A DQYmbuW1AAhmO758McKb+i6O5RYvzmBvYa5PLtB9fxvCCuXxpmWhi1XQkjI3DpyGf9Wb tcam3xyknZvvLf4S1FjXpCBDgFpjD0do6YuMssibmei6FY8wfy6Nt0Ho1pYbvK+Fm0Q5 ogi9hS0UkwAy1SFW9Hg6+AIlIk1DrLcW2Rae5FOACRJSJqu2tzwzj+KuSpnWTaJAuIY0 uciFEij83IKIUYY8YA56k/6BXWW+sn/14KimcibOa5aT4oSlLDKslJEr1sodGjLIOn2c BS5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=mSH6vjaD/nr1X2l9Lu5p2XVHT+RbgtF+8lv2TXUlGxI=; b=QKs0pyn1ZEJjYT2HZXif7M6jTnRDJd7c3+UlGb82LYeTf4M2DYk/2Un9zf5oxH4PD9 Tbghb2N5zuSTWGjCaUrwcNxbSeB3fvnt9Mx1NTwrqWA65CELJUrkqBt13cYLd87CF4xT bxGUvrIZ5icO8JwaHfyYpZPGHHyVc3DwsU+GEUrMRY2O+BD7EH+ps1vdR3Ke1E2QqcTK 1IFOjAP9XsZ2NGGrVFOUAC7xTsKxd/Ty9bqecQl+pbGGW6ZWtSdc1lKdBMuJ3FAJM49o BzqK5VibTOcYkdwL+bzmhMu3r0weOveoDDGszHlguYOl51/QzaI4wuvRjuAgY1yPUwaa 5YTQ== X-Gm-Message-State: APjAAAUkZ+KnzUX2PpahdsmV2u0dOt8aSZy/OqwO1jTlpsaun5kLyGpz eP6oNhboQDjbczTdW9LWU5yf7A== X-Google-Smtp-Source: APXvYqysSME+/cdv9S8P9cj2bcfPJvkEUDZsjH4vh2DbbdzUop8MSCZwew2ErpDpFIMCx2GEjV1qug== X-Received: by 2002:a17:902:a412:: with SMTP id p18mr9930029plq.105.1560289963457; Tue, 11 Jun 2019 14:52:43 -0700 (PDT) Received: from localhost ([2620:0:1000:147d:bc5f:a59e:d0e2:264f]) by smtp.gmail.com with ESMTPSA id y22sm10173193pfm.70.2019.06.11.14.52.42 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 11 Jun 2019 14:52:42 -0700 (PDT) Date: Tue, 11 Jun 2019 14:52:42 -0700 From: Sandeep Patil To: Saravana Kannan Cc: Frank Rowand , Rob Herring , Mark Rutland , Greg Kroah-Hartman , "Rafael J. Wysocki" , David Collins , devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , Android Kernel Team Subject: Re: [RESEND PATCH v1 1/5] of/platform: Speed up of_find_device_by_node() Message-ID: <20190611215242.GE212690@google.com> References: <20190604003218.241354-1-saravanak@google.com> <20190604003218.241354-2-saravanak@google.com> <570474f4-8749-50fd-5f72-36648ed44653@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 11, 2019 at 01:56:25PM -0700, 'Saravana Kannan' via kernel-team wrote: > On Tue, Jun 11, 2019 at 8:18 AM Frank Rowand wrote: > > > > Hi Saravana, > > > > On 6/10/19 10:36 AM, Rob Herring wrote: > > > Why are you resending this rather than replying to Frank's last > > > comments on the original? > > > > Adding on a different aspect... The independent replies from three different > > maintainers (Rob, Mark, myself) pointed out architectural issues with the > > patch series. There were also some implementation issues brought out. > > (Although I refrained from bringing up most of my implementation issues > > as they are not relevant until architecture issues are resolved.) > > Right, I'm not too worried about the implementation issues before we > settle on the architectural issues. Those are easy to fix. > > Honestly, the main points that the maintainers raised are: > 1) This is a configuration property and not describing the device. > Just use the implicit dependencies coming from existing bindings. > > I gave a bunch of reasons for why I think it isn't an OS configuration > property. But even if that's not something the maintainers can agree > to, I gave a concrete example (cyclic dependencies between clock > provider hardware) where the implicit dependencies would prevent one > of the devices from probing till the end of time. So even if the > maintainers don't agree we should always look at "depends-on" to > decide the dependencies, we still need some means to override the > implicit dependencies where they don't match the real dependency. Can > we use depends-on as an override when the implicit dependencies aren't > correct? > > 2) This doesn't need to be solved because this is just optimizing > probing or saving power ("we should get rid of this auto disabling"): > > I explained why this patch series is not just about optimizing probe > ordering or saving power. And why we can't ignore auto disabling > (because it's more than just auto disabling). The kernel is currently > broken when trying to use modules in ARM SoCs (probably in other > systems/archs too, but I can't speak for those). > > 3) Concerns about backwards compatibility > > I pointed out why the current scheme (depends-on being the only source > of dependency) doesn't break compatibility. And if we go with > "depends-on" as an override what we could do to keep backwards > compatibility. Happy to hear more thoughts or discuss options. > > 4) How the "sync_state" would work for a device that supplies multiple > functionalities but a limited driver. To be clear, all of above are _real_ problems that stops us from efficiently load device drivers as modules for Android. So, if 'depends-on' doesn't seem like the right approach and "going back to the drawing board" is the ask, could you please point us in the right direction? - ssp