From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759179Ab3BNKv1 (ORCPT ); Thu, 14 Feb 2013 05:51:27 -0500 Received: from hqemgate03.nvidia.com ([216.228.121.140]:7949 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757358Ab3BNKvZ (ORCPT ); Thu, 14 Feb 2013 05:51:25 -0500 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Thu, 14 Feb 2013 02:47:29 -0800 Message-ID: <511CC194.8010206@nvidia.com> Date: Thu, 14 Feb 2013 16:21:00 +0530 From: Laxman Dewangan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121028 Thunderbird/16.0.2 MIME-Version: 1.0 To: Stephen Warren CC: "mturquette@linaro.org" , Stephen Warren , Prashant Gaikwad , Peter De Schrijver , "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" Subject: Re: [PATCH V2] clk: tegra: initialise parent of uart clocks References: <1360682279-23051-1-git-send-email-ldewangan@nvidia.com> <511A7FF1.1030009@wwwdotorg.org> <511B3AA0.7020403@nvidia.com> <511BC0AC.2010101@wwwdotorg.org> In-Reply-To: <511BC0AC.2010101@wwwdotorg.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 13 February 2013 10:04 PM, Stephen Warren wrote: > On 02/13/2013 12:02 AM, Laxman Dewangan wrote: >> On Tuesday 12 February 2013 11:16 PM, Stephen Warren wrote: >>> On 02/12/2013 08:17 AM, Laxman Dewangan wrote: >>>> Initialise the parent of UARTs to PLLP and disabling clock by >>>> default. >>> This patch wasn't tested, was it? Without the patch I just sent titled >>> "ARM: tegra: remove clock-frequency properties from serial nodes", the >>> UART clocks get turned off and the console breaks. >> I tested this in next-20130212 where "clock-frequency" is there in >> tegra30.dtsi file. > I tested on Cardhu/Tegra30 (I'd previously only tested on > Harmony/Tegra20), and I see the exact same problem; the clock core turns > off the UART clock and the system hangs. > > Are you sure you don't have any other local patches that somehow keep > the UART clock on (e.g. disabling clk_disable_unused, calling clk_get() > on the UART clock somewhere else, have the Tegra HS UART driver enabled > on the console port for testing which perhaps does an unconditional > clk_get). Are you sure you're testing with U-Boot rather than our binary > bootloader; who knows what kind of voodoo that does to clocks. > > Note: I tested: a merge of arm-soc/for-next and Tegra's for-next branch, > with my patch to remove the clock-frequency properties reverted, plus a > fix for the boot crash ("clockevents: fix generic broadcast for > FEAT_C3STOP"). > >> If you remove this from dts file at all then it will not work as there >> is no execution path to call the clk_prepare_enable(). >> >> of_serial.c file: >> if (of_property_read_u32(np, "clock-frequency", &clk)) { > That returns 0 if the property is present (so doesn't get/enable the > clock), and an error code if the property is missing (so does get/enable > the clock). Ahha..Yes, got it. I tested this in next-20130212 with the maintainer's patch for broadcast, reverting one change "OF: convert devtree lock from rw_lock to raw spinlock" and uart clock change. The system was booting but not reaching to login. I was assumign that it may be the issue with other reason as I saw the uart log. After taking your patch for removing clock-freq and this patch, the system booted to login prompt means it is working fine. So I was wrong when telling clock-frequency is required. Actually it should not be to work properly.