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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 E1FCDC4332B for ; Wed, 10 Feb 2021 13:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1D9664E7E for ; Wed, 10 Feb 2021 13:03:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231774AbhBJNCu (ORCPT ); Wed, 10 Feb 2021 08:02:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231701AbhBJM6J (ORCPT ); Wed, 10 Feb 2021 07:58:09 -0500 Received: from mail.marcansoft.com (marcansoft.com [IPv6:2a01:298:fe:f::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65895C061574; Wed, 10 Feb 2021 04:56:15 -0800 (PST) Received: from [127.0.0.1] (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: marcan@marcan.st) by mail.marcansoft.com (Postfix) with ESMTPSA id B7B3541FA3; Wed, 10 Feb 2021 12:56:10 +0000 (UTC) Subject: Re: [PATCH 18/18] arm64: apple: Add initial Mac Mini 2020 (M1) devicetree To: Daniel Palmer List-Id: Cc: Tony Lindgren , Arnd Bergmann , DTML , Marc Zyngier , Linux Kernel Mailing List , Krzysztof Kozlowski , SoC Team , Rob Herring , Olof Johansson , linux-arm-kernel References: <20210204203951.52105-1-marcan@marcan.st> <20210204203951.52105-19-marcan@marcan.st> <20210208110441.25qc6yken4effd6c@kozik-lap> <4481998a-27f6-951e-bb4f-a9d2b95f211f@marcan.st> <4dd911d8-ce84-bf4d-3aae-95ef321b4a97@marcan.st> From: Hector Martin Message-ID: <3d61ca6d-98a1-b78a-07da-cd20834de5a1@marcan.st> Date: Wed, 10 Feb 2021 21:56:08 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: es-ES Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/02/2021 21.24, Daniel Palmer wrote: > This exact problem exists for MStar/SigmaStar too. > As it stands there is no documentation to show what the actual clock > tree looks like so everything is guess and I need to come up with numbers. > I'm interested to see what the solution to this is as it will come up again > when mainlining chips without documentation. So far the answer seems to be to take the best guess available, and then we get to fix it until we have real users and breaking DT compatibility is no longer an option... :-) >> The purpose of the clock in this particular case is just to make the >> uart driver work, since it wants to know its reference clock; there is >> work to be done here to figure out the real clock tree > > FWIW arm/boot/dts/mstar-v7.dtsi has the same issue: Needs uart, > has no uart clock. In that instance the uart clock setup by u-boot > is passed to the uart driver as a property instead of creating a fake > clock. In our case it's an existing driver (with patches) that is already integrated with the clock infrastructure, so it makes sense to use a fixed-clock instead of just an ad-hoc property. -- Hector Martin (marcan@marcan.st) Public Key: https://mrcn.st/pub