Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754168Ab2KLVWn (ORCPT ); Mon, 12 Nov 2012 16:22:43 -0500 Received: from comal.ext.ti.com ([198.47.26.152]:41839 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754044Ab2KLVWl convert rfc822-to-8bit (ORCPT ); Mon, 12 Nov 2012 16:22:41 -0500 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT To: Shiraz Hashim , Rob Herring From: Mike Turquette In-Reply-To: CC: , , Viresh Kumar , References: Message-ID: <20121112212212.20034.78522@nucleus> User-Agent: alot/0.3.2+ Subject: Re: possibility of parent clock selection through DT Date: Mon, 12 Nov 2012 13:22:12 -0800 X-Originating-IP: [10.188.36.112] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1565 Lines: 40 Quoting Shiraz Hashim (2012-11-06 22:36:10) > On Wed, Nov 7, 2012 at 11:42 AM, Shiraz Hashim > wrote: > > Hi Mike, Rob, > > > > Devices in a SoC can have multiple possible clock sources which is > > perfectly captured through clk framework. > > > > But the device itself may not be aware of the complex hierarchy above it. > > In this case how do you suggest a board (through DT) should select its > > preference. > > > > Is there some work already going on in this direction ? > > Just to make it clear, I already have referred the clock DT bindings and > Shawn Guo patch on removing clk look up registration from kernel code. > > Here I am talking about possibility of selecting desired clock hierarchy > by the boards about which device nodes are not aware. > One way to achieve this is to use clk_set_rate as a way to switch parents at run-time. The OMAP CCF code currently does this when relocking PLLs and makes use of __clk_reparent to update the clock framework's representation of the hierarchy dynamically. Maybe something like the following is helpful to you: http://git.linaro.org/gitweb?p=people/mturquette/linux.git;a=blob;f=arch/arm/mach-omap2/dpll3xxx.c;h=f72dedb4eee892ce4cd5bdf22cc8c22510f3d526;hb=clk-omap-3.8#l542 Regards, Mike > -- > regards > Shiraz Hashim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/