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 11:42:24 -0700 Message-ID: <20171019184223.GA7415@Asurada-Nvidia> References: <1505502613-11801-1-git-send-email-nicoleotsuka@gmail.com> <20171019092919.GA7252@Asurada> <20171019094422.GI9005@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20171019094422.GI9005@ulmo> Sender: linux-clk-owner@vger.kernel.org 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 List-Id: linux-tegra@vger.kernel.org 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 cases should be irqs_disabled(). Thanks Nicolin