Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756361AbcCWRbW (ORCPT ); Wed, 23 Mar 2016 13:31:22 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:50874 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751835AbcCWRbU (ORCPT ); Wed, 23 Mar 2016 13:31:20 -0400 Subject: Re: [PATCH v2 03/11] ARM: davinci: da850: use clk->set_parent for async3 To: David Lechner References: <1458181615-27782-1-git-send-email-david@lechnology.com> <1458181615-27782-4-git-send-email-david@lechnology.com> <56F2BCAB.3040404@ti.com> <56F2D05C.8030909@lechnology.com> CC: Petr Kulhavy , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Kevin Hilman , Kishon Vijay Abraham I , Alan Stern , Greg Kroah-Hartman , Bin Liu , Robert Jarzmik , =?UTF-8?Q?Andreas_F=c3=a4rber?= , Tony Lindgren , Sergei Shtylyov , , , , From: Sekhar Nori Message-ID: <56F2D27F.6040001@ti.com> Date: Wed, 23 Mar 2016 22:59:35 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <56F2D05C.8030909@lechnology.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2008 Lines: 49 On Wednesday 23 March 2016 10:50 PM, David Lechner wrote: > On 03/23/2016 10:56 AM, Sekhar Nori wrote: >> On Thursday 17 March 2016 07:56 AM, David Lechner wrote: >>> The da850 family of processors has an async3 clock domain that can be >>> muxed to either pll0_sysclk2 or pll1_sysclk2. Now that the davinci >>> clocks >>> have a set_parent callback, we can use this to control the async3 mux >>> instead of a stand-alone function. >>> >>> This adds a new async3_clk and sets the appropriate child clocks. The >>> default is use to pll1_sysclk2 since it is not affected by processor >>> frequency scaling. >>> >>> Signed-off-by: David Lechner >>> --- >> >>> +static int da850_async3_set_parent(struct clk *clk, struct clk *parent) >>> +{ >>> + u32 __iomem *cfgchip3; >>> + u32 val; >>> + >>> + /* >>> + * Can't use DA8XX_SYSCFG0_VIRT() here since this can be called >>> before >>> + * da8xx_syscfg0_base is initialized. >>> + */ >>> + cfgchip3 = ioremap(DA8XX_SYSCFG0_BASE + DA8XX_CFGCHIP3_REG, 4); >> >> Is this just a theoretical possibility or have you seen this happen? I >> would like to see if there are ways of avoiding this rather than throw >> away usage of DA8XX_SYSCFG0_VIRT() > > Yes, it will not boot without this. The problem comes from the fact that > clocks are setup in davinci_common_init() which is called before > da8xx_syscfg0_base = ioremap(DA8XX_SYSCFG0_BASE, SZ_4K) in da850_init() > (and da830_init()). I also tried moving the ioremap() before > davinci_common_init(), but davinci_common_init() sets up the iomem, so > that doesn't work either. > > So, if you want to use DA8XX_SYSCFG0_VIRT() here, the clock init would > have to be split out from davinci_common_init() which would affect all > davinci devices. Alright, I guess 'can be called' in the comment should have used stronger language :) How about late registration of USB clocks as I suggested. It should also help consolidate code across da830 and da850. Thanks, Sekhar