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 7557AC18E5B for ; Tue, 10 Mar 2020 04:19:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5323B2467D for ; Tue, 10 Mar 2020 04:19:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="UezJBUd8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726295AbgCJETH (ORCPT ); Tue, 10 Mar 2020 00:19:07 -0400 Received: from mail-pj1-f66.google.com ([209.85.216.66]:52683 "EHLO mail-pj1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbgCJETH (ORCPT ); Tue, 10 Mar 2020 00:19:07 -0400 Received: by mail-pj1-f66.google.com with SMTP id f15so843357pjq.2 for ; Mon, 09 Mar 2020 21:19:05 -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=/nvpQDa2s0MPVMjqN65EPRdkP1shvWxs57ggK4I2Mg4=; b=UezJBUd8UBFyj3bKah7Qw2Wo2AtojekX2ufF2g3ZSYIv0sEUqPhtk3IYefMBkbFntK niMJRQRYZqV+HvnHSDhBuzfxA+FDgFL2zorgk2mt8cw8NOd0wRXCkT9vIlXB1FMqh7tj OhCrI5/4S94tcBaKvKOHcE0C0xEd3yz7AxbBO8utT20BqpRcb95IClwp8iF3E/mhmNJK k8idTur7D8G3lVXh5CbfP5dUkZ6EqQd2BZuBB/nPHy90/EYLxBe4DkL80Qym9ZhPji7G ssk8cc4aoVvAed8Eu92Mtdan/qI7hNq+tSfTBhm3aUKgMB/B9ntD3C9Elj0xr6AtGbp3 ozHg== 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=/nvpQDa2s0MPVMjqN65EPRdkP1shvWxs57ggK4I2Mg4=; b=q9VricIrwHVxHi3I8IT2R7cecBEM+4mmyNivmjtEYxVFZQwnoN5SD58W3wmZTSrQQX dQyAid3idEgAF/Rbvf9qU1stpl2qZVNWdXc19AK5BivtKhucEP3OHUY0M5y4GN+BLcjW NzHr6QxHJKMMXQcDLB8fmOMJyLX6osmeGpe5uxSvfWJR5968EUOanTLXqPtuf6UsEGCO iwlmxGPIlmtH9Vcbog+lpxMVYMLGbyBXktqgDDld3JtFZzKAQJIoycO6E/X52dw7vzcE r8JIreY0KwcPiwfJbfz1p4gh6a6CriXYWh4uDJ30bj4VCfm6fdrB6wEIW63+UwxL3XwB JaSg== X-Gm-Message-State: ANhLgQ2KMrnTw18feUO3pQb6wNsWbtnV4IoGeTK+0y8MGKDNLDNXrIvz khbhGN6vVY79D8ZrkzpfjHaLTA== X-Google-Smtp-Source: ADFU+vutaDK0+h41+jM+ieqjovHYAnMwRD0e/via06npv351pht7qAqbdVGySjzm9/g9/OXDlq5GNA== X-Received: by 2002:a17:902:ab8e:: with SMTP id f14mr18389189plr.339.1583813944702; Mon, 09 Mar 2020 21:19:04 -0700 (PDT) Received: from localhost ([2620:15c:211:0:fb21:5c58:d6bc:4bef]) by smtp.gmail.com with ESMTPSA id 128sm33508515pfe.163.2020.03.09.21.19.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2020 21:19:03 -0700 (PDT) Date: Mon, 9 Mar 2020 21:19:03 -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: <20200310041903.GA260998@google.com> References: <20200305103228.9686-1-zhang.lyra@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org 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) Thanks, - ssp