From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752471AbbKYPwR (ORCPT ); Wed, 25 Nov 2015 10:52:17 -0500 Received: from mail-ig0-f175.google.com ([209.85.213.175]:38630 "EHLO mail-ig0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751194AbbKYPwO (ORCPT ); Wed, 25 Nov 2015 10:52:14 -0500 MIME-Version: 1.0 In-Reply-To: <20151125151100.GA31492@ulmo.nvidia.com> References: <1448032264-29622-1-git-send-email-jonathanh@nvidia.com> <20151125151100.GA31492@ulmo.nvidia.com> Date: Wed, 25 Nov 2015 07:52:13 -0800 Message-ID: Subject: Re: [PATCH] clk: tegra: Fix bypassing of PLLs From: Tyler Baker To: Thierry Reding Cc: Jon Hunter , Peter De Schrijver , Prashant Gaikwad , Michael Turquette , Stephen Boyd , Stephen Warren , Alexandre Courbot , linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, "linux-kernel@vger.kernel.org" , Rhyland Klein , "Kevin's boot bot" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25 November 2015 at 07:11, Thierry Reding wrote: > On Mon, Nov 23, 2015 at 03:18:59PM -0800, Tyler Baker wrote: >> Hi Jon, >> >> On 20 November 2015 at 07:11, Jon Hunter wrote: >> > The _clk_disable_pll() function will attempt to place a PLL into bypass >> > if the TEGRA_PLL_BYPASS is specified for the PLL and then disable the PLL >> > by clearing the enable bit. To place the PLL into bypass, the bypass bit >> > needs to be set and not cleared. Fix this by setting the bypass bit and >> > not clearing it. >> > >> > Signed-off-by: Jon Hunter >> >> The kernelci.org bot recently detected a jetson-tk1 boot failure[1][2] >> in the tegra tree. This boot failure has only been observed when >> booting with a multi_v7_defconfig kernel variant. The bot bisected[3] >> this boot failure to this commit, and I confirmed reverting it on top >> of the tegra for-next branch resolves the issue. The ramdisk[4] used >> for booting is loaded with the modules from the build. It appears to >> me that as the modules are being loaded in userspace by eudev the >> jetson-tk1 locks up. I've sifted through the console logs a bit, and >> found this splat to be most interesting[5]. Can you confirm this >> issue on your end? > > Just to close the loop on this: we've discussed this on IRC and came to > the conclusion that not using the bypass mode is safer (switching into > and out of bypass can glitch). I've dropped this patch for now and Jon > will be looking into a second revision of the patch which, in addition > to fixing bypass (the fix is legit, it just happens to break because of > the glitch, most likely), will also remove the BYPASS flag setting so > that bypass will not be used. Thanks for the update, I appreciate you guys looking into this issue. Please CC me on any fixes, I can re-test and give my tested-by. Cheers, Tyler