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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 EE672C433FF for ; Fri, 2 Aug 2019 13:38:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7E0B20679 for ; Fri, 2 Aug 2019 13:38:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="KtMVOER5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390829AbfHBNiu (ORCPT ); Fri, 2 Aug 2019 09:38:50 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:17476 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725886AbfHBNiu (ORCPT ); Fri, 2 Aug 2019 09:38:50 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 02 Aug 2019 06:38:50 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Fri, 02 Aug 2019 06:38:49 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Fri, 02 Aug 2019 06:38:49 -0700 Received: from tbergstrom-lnx.Nvidia.com (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 2 Aug 2019 13:38:49 +0000 Received: by tbergstrom-lnx.Nvidia.com (Postfix, from userid 1000) id A848640DF8; Fri, 2 Aug 2019 16:38:46 +0300 (EEST) Date: Fri, 2 Aug 2019 16:38:46 +0300 From: Peter De Schrijver To: Dmitry Osipenko CC: Thierry Reding , Jonathan Hunter , , Subject: Re: [PATCH v3 1/2] soc/tegra: pmc: Query PCLK clock rate at probe time Message-ID: <20190802133846.GC3883@pdeschrijver-desktop.Nvidia.com> References: <20190730174020.15878-1-digetx@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20190730174020.15878-1-digetx@gmail.com> X-NVConfidentiality: public User-Agent: Mutt/1.9.4 (2018-02-28) X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1564753130; bh=NYPEReOcRkEt8FjbS9Ttl4NUHHl3iyUby0ueHEMmSyQ=; h=X-PGP-Universal:Date:From:To:CC:Subject:Message-ID:References: MIME-Version:Content-Type:Content-Disposition:In-Reply-To: X-NVConfidentiality:User-Agent:X-Originating-IP:X-ClientProxiedBy; b=KtMVOER5BAZ79dnaHAglxnwjYTORHllqJFYpHOTov9xotK+yRUsxg7dCX2IUMAWHI p+7Pecyd5NJfdvWVKtlMgr/5yUCy3aWIyB4Tek/9NB2z69i8Mp1oMy1hQMe2fKocqi ahjM2fvTQvUWAOYNw8vrnXHui6kvoc5FJsonj60RVip916HYohf0OctXezra/VrRY4 wdhYfjoYIYD1wnYb+0iMLwoXmoDnX+RAvNptqOyjFHTZYVd4wshwfDlQWfdYlJf60f bWlZjRlXxQI3eFjOgy8BX/Vskl3vW9wdYQbAPIeELYEGPwmsdW9Wq3SSeiIsnJ6/4o ZZmQN/PDUhCrw== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 30, 2019 at 08:40:19PM +0300, Dmitry Osipenko wrote: > The PCLK clock is running off SCLK, which is a critical clock that is > very unlikely to randomly change its rate. It is possible to get a > lockup if kernel decides to enter LP2 cpuidle from a clk-notifier, which > happens occasionally in a case of Tegra30 EMC driver that waits for the > clk-change event in the clk-notify handler, because CCF's 'prepare' mutex > in kept locked and thus clk_get_rate() wants to sleep with interrupts > being disabled. > I don't think this is the right solution. Eventually we will want to scale sclk and pclk because the clock tree power of those is not insignificant. Maybe register a notifier which updates the PMC timer values when pclk changes? Peter.