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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 30F33C10F27 for ; Tue, 10 Mar 2020 04:27:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 04B2424655 for ; Tue, 10 Mar 2020 04:27:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="vso8Su7f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726211AbgCJE1o (ORCPT ); Tue, 10 Mar 2020 00:27:44 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:42788 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725865AbgCJE1o (ORCPT ); Tue, 10 Mar 2020 00:27:44 -0400 Received: by mail-pf1-f194.google.com with SMTP id f5so5870542pfk.9 for ; Mon, 09 Mar 2020 21:27:42 -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=C1l6HjZC0sgmgnUyratSp4inFmRTQZVJyoMKu8hDcSA=; b=vso8Su7fdlIlzNH9YFMFH5fNnH4gku7soDfmnTr+2lqkUbAFfY1TMtZmVzX9D181kw GJibMG2ILmZzmpxkK/RDqbX9FTnXnd9mmHJd/0j8Yqs+nJZI9xor1ajaye7cFF1+e9Xx 1SHHAckPT1AIgCO49r956ndOEmYE3nHsgYzWCBlutZBR6uKkMRPCp/sEOdPLzsfJ/I71 0nrYXRkQmeH3EwZUCO77iWPu75iubzgPdDBkrpMFCw17UR8Sr637eZn0o/Rf3k3r0KKN 9eDGOm6KUtUnQkH/jVU/be08kRh5A03/b9+xUMbyDTzZLeBL3Ye/UP8L8ywC5Aagevqj Ic5w== 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=C1l6HjZC0sgmgnUyratSp4inFmRTQZVJyoMKu8hDcSA=; b=nzTwPQP4T7vYItKaWj4abYGW3UuyR2VgzAY9q7BmQnfSwNvqrSTRucSnoKCwiHNoYs 7lt1ZgvPzEzopOEWWHXxeFp9QIa2P57Bpz0HQicpjb9ZVrWARnQHMq+wh60daFrwLcIg OAiwhR9OTHU0shdJepRsMLx1Zy1hO1xuDdQNrGdomwH8CEn7YcUSYvtFAJDkLlvJAZRB 8wu+62AYuW0743mCZfaz2jO9DpSag/LMfyuNzl5j+uF5FKN3Y8WiYF/ctdwuO1CUPTi2 eTk92seAMdPQI0hTQG47Srndfszs2XK+jab6yFixrsZo57Quuq6QbYhsbCpa63S3TBDV XzAA== X-Gm-Message-State: ANhLgQ0W/CsZ8XJkGiUfT9GBCyZVAdDrxP2NAX7jwI1ZaAnQBWn3Zf7i DNFeeRfC1mjSlm49uhLeXQQDGg== X-Google-Smtp-Source: ADFU+vvXQ+QpS438H68hfpmZX/YRRGV9nQnNQNVwr3CqfTOUPOMN9I6CdQrKvqRjiZxRpG1cZ2Up8w== X-Received: by 2002:aa7:97ba:: with SMTP id d26mr19515920pfq.65.1583814461641; Mon, 09 Mar 2020 21:27:41 -0700 (PDT) Received: from localhost ([2620:15c:211:0:fb21:5c58:d6bc:4bef]) by smtp.gmail.com with ESMTPSA id ev22sm1009815pjb.4.2020.03.09.21.27.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2020 21:27:41 -0700 (PDT) Date: Mon, 9 Mar 2020 21:27:39 -0700 From: Sandeep Patil To: Geert Uytterhoeven Cc: Chunyan Zhang , Greg Kroah-Hartman , Catalin Marinas , Will Deacon , Jiri Slaby , Linux Kernel Mailing List , Chunyan Zhang , "open list:SERIAL DRIVERS" , Baolin Wang , Orson Zhai , Linux ARM , Android Kernel Team , saravanak@google.com Subject: Re: [PATCH 1/2] arm64: change ARCH_SPRD Kconfig to tristate Message-ID: <20200310042739.GB260998@google.com> References: <20200305103228.9686-1-zhang.lyra@gmail.com> <20200310041903.GA260998@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200310041903.GA260998@google.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 09, 2020 at 09:19:03PM -0700, Sandeep Patil wrote: > Hi Geert, > > On Mon, Mar 09, 2020 at 11:32:06AM +0100, Geert Uytterhoeven wrote: > > Hi Chunyan, > > > > On Mon, Mar 9, 2020 at 9:32 AM Chunyan Zhang wrote: > > > On Mon, 9 Mar 2020 at 16:03, Geert Uytterhoeven wrote: > > > > On Thu, Mar 5, 2020 at 11:33 AM Chunyan Zhang wrote: > > > > > From: Chunyan Zhang > > > > > > > > > > The default value of Kconfig for almost all sprd drivers are the same with > > > > > ARCH_SPRD, making these drivers built as modules as default would be easier > > > > > if we can set ARCH_SPRD as 'm', so this patch change ARCH_SPRD to tristate. > > > > > > > > > > Signed-off-by: Chunyan Zhang > > > > > > > > Can you actually boot a kernel on a Spreadtrum platform when all platform > > > > and driver support is modular? > > > > > > Yes, even if all drivers are modular. > > > > Cool. No hard dependencies on e.g. regulators that are turned off when > > unused? > > > > > But I hope serial can be builtin, then I can have a console to see > > > kernel output before loading modules. > > > > No dependency on the clock driver? > > Oh, I see you have a hack in the serial driver, to assume default > > values when the serial port's parent clock is not found. That may > > limit use of the other serial ports, depending on the actual serial > > hardware. > > And on Sharkl64, the serial port's clock is a fixed-clock anyway, so > > you don't even need the hack. > > > > But in general you cannot rely on that, especially if your SoC has clock > > and/or power domains. > > > > BTW, what about the watchdog driver? That one does need a clock, and > > loading it too late will reboot your system. > > > > > Also, this's what Google GKI [1] asked :) > > > > > > Regards, > > > Chunyan > > > > > > [1] https://arstechnica.com/gadgets/2019/11/google-outlines-plans-for-mainline-linux-kernel-support-in-android/ > > > > Let's see how having everything modular works out on an SoC where all > > hardware is part of a clock and power domain. > > I'm curious, are there any problems that we should be aware of? We know about > the regulator sync state and consumer-supplier dependencies. [1] > > (Adding Saravana inline) > (oops, forgot to paste the link to presentation) 1. https://linuxplumbersconf.org/event/4/contributions/402/attachments/320/544/Solving_issues_associated_with_modules_and_supplier-consumer_dependencies.pdf