From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolin Chen Subject: Re: [PATCH v2] clk: tegra: Use readl_relaxed_poll_timeout_atomic in tegra210_clock_init Date: Thu, 19 Oct 2017 17:19:01 -0700 Message-ID: <20171020001859.GA9196@Asurada-Nvidia> References: <1505502613-11801-1-git-send-email-nicoleotsuka@gmail.com> <20171019092919.GA7252@Asurada> <20171019094422.GI9005@ulmo> <20171019184223.GA7415@Asurada-Nvidia> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20171019184223.GA7415@Asurada-Nvidia> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, pdeschrijver-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, mturquette-rdvid1DuHRBWk0Htik3J/w@public.gmane.org, pgaikwad-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On Thu, Oct 19, 2017 at 11:42:24AM -0700, Nicolin Chen wrote: > On Thu, Oct 19, 2017 at 11:44:22AM +0200, Thierry Reding wrote: > > > > Below is the call trace of tegra210_init_pllu() function: > > > > start_kernel() > > > > -> time_init() > > > > --> of_clk_init() > > > > ---> tegra210_clock_init() > > > > ----> tegra210_pll_init() > > > > -----> tegra210_init_pllu() > > > I'm wondering why we're not seeing a splat for this. Usually the kernel > > will warn if you sleep during atomic context. Does this mean we're just > > not hitting that case? > > Yes. > > > readx_poll_timeout() has a might_sleep_if(), and > > therefore it should always cause the splat. > > That's true as long as CONFIG_DEBUG_ATOMIC_SLEEP is enabled locally. > > > Any ideas why this has gone unnoticed for all this time? > > We can see in the tegra210_init_pllu() function that it'll not call > tegra210_enable_pllu() if pllu is already enabled (by bootloader). > > You can verify it by adding an irqs_disabled() in this routine. The > function is called during system-boot and suspend-n-resume. And both A correction: using mainline kernel, only system-boot as the commit log describes. > cases should be irqs_disabled(). > > Thanks > Nicolin From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751601AbdJTATL (ORCPT ); Thu, 19 Oct 2017 20:19:11 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:48741 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751112AbdJTATJ (ORCPT ); Thu, 19 Oct 2017 20:19:09 -0400 X-Google-Smtp-Source: ABhQp+RN2N64xDhQOTOmadS/oKoZUhqqZEwWwdP5UaDoKc0QYOyGCXhzT7VmUaL38C2/UQTCteQbdQ== Date: Thu, 19 Oct 2017 17:19:01 -0700 From: Nicolin Chen To: Thierry Reding Cc: sboyd@codeaurora.org, pdeschrijver@nvidia.com, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org, linux-clk@vger.kernel.org, jonathanh@nvidia.com, mturquette@baylibre.com, pgaikwad@nvidia.com Subject: Re: [PATCH v2] clk: tegra: Use readl_relaxed_poll_timeout_atomic in tegra210_clock_init Message-ID: <20171020001859.GA9196@Asurada-Nvidia> References: <1505502613-11801-1-git-send-email-nicoleotsuka@gmail.com> <20171019092919.GA7252@Asurada> <20171019094422.GI9005@ulmo> <20171019184223.GA7415@Asurada-Nvidia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171019184223.GA7415@Asurada-Nvidia> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 19, 2017 at 11:42:24AM -0700, Nicolin Chen wrote: > On Thu, Oct 19, 2017 at 11:44:22AM +0200, Thierry Reding wrote: > > > > Below is the call trace of tegra210_init_pllu() function: > > > > start_kernel() > > > > -> time_init() > > > > --> of_clk_init() > > > > ---> tegra210_clock_init() > > > > ----> tegra210_pll_init() > > > > -----> tegra210_init_pllu() > > > I'm wondering why we're not seeing a splat for this. Usually the kernel > > will warn if you sleep during atomic context. Does this mean we're just > > not hitting that case? > > Yes. > > > readx_poll_timeout() has a might_sleep_if(), and > > therefore it should always cause the splat. > > That's true as long as CONFIG_DEBUG_ATOMIC_SLEEP is enabled locally. > > > Any ideas why this has gone unnoticed for all this time? > > We can see in the tegra210_init_pllu() function that it'll not call > tegra210_enable_pllu() if pllu is already enabled (by bootloader). > > You can verify it by adding an irqs_disabled() in this routine. The > function is called during system-boot and suspend-n-resume. And both A correction: using mainline kernel, only system-boot as the commit log describes. > cases should be irqs_disabled(). > > Thanks > Nicolin