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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 26BA3C433E6 for ; Wed, 20 Jan 2021 16:16:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA177233EB for ; Wed, 20 Jan 2021 16:16:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391463AbhATQP5 (ORCPT ); Wed, 20 Jan 2021 11:15:57 -0500 Received: from inva020.nxp.com ([92.121.34.13]:54940 "EHLO inva020.nxp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390773AbhATQPM (ORCPT ); Wed, 20 Jan 2021 11:15:12 -0500 Received: from inva020.nxp.com (localhost [127.0.0.1]) by inva020.eu-rdc02.nxp.com (Postfix) with ESMTP id 1C4141A0A74; Wed, 20 Jan 2021 17:14:22 +0100 (CET) Received: from inva024.eu-rdc02.nxp.com (inva024.eu-rdc02.nxp.com [134.27.226.22]) by inva020.eu-rdc02.nxp.com (Postfix) with ESMTP id 0FA461A013D; Wed, 20 Jan 2021 17:14:22 +0100 (CET) Received: from localhost (fsr-ub1664-175.ea.freescale.net [10.171.82.40]) by inva024.eu-rdc02.nxp.com (Postfix) with ESMTP id EEC892039A; Wed, 20 Jan 2021 17:14:21 +0100 (CET) Date: Wed, 20 Jan 2021 18:14:21 +0200 From: Abel Vesa To: Sascha Hauer Cc: Adam Ford , arm-soc , Adam Ford-BE , Aisheng Dong , Michael Turquette , Stephen Boyd , Shawn Guo , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Linus Walleij , Jerome Brunet , linux-clk , Linux Kernel Mailing List Subject: Re: [PATCH V3] clk: imx: Fix reparenting of UARTs not associated with sdout Message-ID: <20210120161421.h3yng57m3fetwwih@fsr-ub1664-175> References: <20210115182909.314756-1-aford173@gmail.com> <20210118125204.hxsanoohwvdtdvym@fsr-ub1664-175> <20210120144454.f6b72lnasw4q3bde@fsr-ub1664-175> <20210120151305.GC19063@pengutronix.de> <20210120152813.x2pbs5vprevkly23@fsr-ub1664-175> <20210120155001.GD19063@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210120155001.GD19063@pengutronix.de> User-Agent: NeoMutt/20180622 X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21-01-20 16:50:01, Sascha Hauer wrote: > On Wed, Jan 20, 2021 at 05:28:13PM +0200, Abel Vesa wrote: > > On 21-01-20 16:13:05, Sascha Hauer wrote: > > > Hi Abel, > > > > > > On Wed, Jan 20, 2021 at 04:44:54PM +0200, Abel Vesa wrote: > > > > On 21-01-18 08:00:43, Adam Ford wrote: > > > > > On Mon, Jan 18, 2021 at 6:52 AM Abel Vesa wrote: > > > > ... > > > > > > > > > > > > > > > > > > > TBH, I'm against the idea of having to call consumer API from a clock provider driver. > > > > > > I'm still investigating a way of moving the uart clock control calls in drivers/serial/imx, > > > > > > where they belong. > > > > > > > > > > That makes sense. > > > > > > > > > > > > > Just a thought. The uart clock used for console remains on from u-boot, > > > > so maybe it's enough to just add the CLK_IGNORE_UNUSED flag to all the > > > > uart root clocks and remove the prepare/enable calls for uart clocks > > > > for good. I don't really have a way to test it right now, but maybe > > > > you could give it a try. > > > > > > That would mean that UART clocks will never be disabled, regardless of > > > whether they are used for console or not. That doesn't sound very > > > appealing. > > > > AFAIK, the only uart clock that is enabled by u-boot is the one used for > > the console. Later on, when the serial driver probes, it will enable it itself. > > > > Unless I'm missing something, this is exactly what we need. > > It might enable it, but with CLK_IGNORE_UNUSED the clock won't be > disabled again when a port is closed after usage OK, tell me what I'm getting wrong in the following scenario: U-boot leaves the console uart clock enabled. All the other ones are disabled. Kernel i.MX clk driver registers the uart clocks with flag CLK_IGNORE_UNUSED. Serial driver probes, then enables/disables the clocks when the port opens/closes. The clk_disable_unused will ignore the uart clocks entirely due to the flag.