Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755808Ab1BJKrB (ORCPT ); Thu, 10 Feb 2011 05:47:01 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:57214 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751067Ab1BJKq7 (ORCPT ); Thu, 10 Feb 2011 05:46:59 -0500 Date: Thu, 10 Feb 2011 11:46:39 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Richard Zhao Cc: Ryan Mallon , Nicolas Pitre , Dima Zavin , Lorenzo Pieralisi , Vincent Guittot , linux-sh@vger.kernel.org, Ben Herrenschmidt , Sascha Hauer , linux-kernel@vger.kernel.org, Paul Mundt , Saravana Kannan , Ben Dooks , Russell King , Jeremy Kerr , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC,PATCH 1/3] Add a common struct clk Message-ID: <20110210104639.GZ27982@pengutronix.de> References: <1297233693.242364.862698430999.1.gpush@pororo> <4D52F73A.4010707@bluewatersys.com> <20110210100319.GB24710@b20223-02.ap.freescale.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20110210100319.GB24710@b20223-02.ap.freescale.net> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:215:17ff:fe12:23b0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1994 Lines: 62 Hello, On Thu, Feb 10, 2011 at 06:03:19PM +0800, Richard Zhao wrote: > On Thu, Feb 10, 2011 at 09:21:14AM +1300, Ryan Mallon wrote: > > On 02/09/2011 07:41 PM, Jeremy Kerr wrote: > > > > Hi Jeremy, > > > > Couple more comments below. > > > > ~Ryan > > > [...] > > > +int clk_enable(struct clk *clk) > > > +{ > > > + unsigned long flags; > > > + int ret = 0; > > > + > > > + spin_lock_irqsave(&clk->enable_lock, flags); > > > > WARN_ON(clk->prepare_count == 0); ? > > > > > + if (clk->enable_count == 0 && clk->ops->enable) > > > + ret = clk->ops->enable(clk); > > > > Does it make sense to have a clock with no enable function which still > > returns success from clk_enable? Do we have any platforms which have > > NULL clk_enable functions? > > > > I think that for enable/disable at least we should require platforms to > > provide functions and oops if they have failed to do so. In the rare > > case that a platform doesn't need to do anything for enable/disable they > > can just supply empty functions. > It's possible to be NULL. So are set_rate/get_rate. > Ideally, if it's NULL: > prepare/unprepare: only call parent's prepare/unprepare > enable/disable: only call parent's enable/disable > set_rate: fail > get_rate: reture parent's get_rate > set_parent: fail > get_parent: fail I wouldn't hard-code the parents into the generic functions. But I suggest to provide generic callbacks to do this, e.g. clk_get_rate_from_parent(struct clk *c) { struct clk *parent = clk_get_parent(c); return clk_get_rate(parent); } Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-K?nig | Industrial Linux Solutions | http://www.pengutronix.de/ | -- 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/