Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753655Ab2KSP7C (ORCPT ); Mon, 19 Nov 2012 10:59:02 -0500 Received: from londo.lunn.ch ([80.238.139.98]:42078 "EHLO londo.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753494Ab2KSP7B (ORCPT ); Mon, 19 Nov 2012 10:59:01 -0500 Date: Mon, 19 Nov 2012 16:58:56 +0100 From: Andrew Lunn To: Thomas Petazzoni Cc: Andrew Lunn , Gregory CLEMENT , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth Subject: Re: [PATCH 1/2] clk: mvebu: armada 370/XP add clock gating control provider for DT Message-ID: <20121119155856.GL10259@lunn.ch> References: <1353014906-31566-6-git-send-email-andrew@lunn.ch> <1353088920-17458-1-git-send-email-gregory.clement@free-electrons.com> <1353088920-17458-2-git-send-email-gregory.clement@free-electrons.com> <20121117082602.GF24569@lunn.ch> <50A75BB4.4070003@free-electrons.com> <20121117135435.GA13479@lunn.ch> <20121119164611.2e754b64@skate> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121119164611.2e754b64@skate> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1631 Lines: 42 On Mon, Nov 19, 2012 at 04:46:11PM +0100, Thomas Petazzoni wrote: > Dear Andrew Lunn, > > On Sat, 17 Nov 2012 14:54:35 +0100, Andrew Lunn wrote: > > > > What is the ddr clock for? Does bad things happen if you turn it off? > > > > Kirkwood has a similar clock, dunit, which i decided not to export, > > > > since when you turn it off, the whole SoC locks up. > > > > > > Well of course if you code run in DDR then it could be a problem. But > > > I think it could be useful to turn it off when going to suspend, it > > > the DDR can do self-refresh. In this case it should be possible to run > > > the code from SRAM or L2 Cache. > > > > O.K. Just watch out for the lateinit call in the clock framework. > > I don't think there is a problem with the dramclk and the lateinit call > of the clock framework. The dramclk is a fixed factor clock, and the > fixed factor clock driver does not implement the ->disable() operation. > And therefore, the clk_disable_unused() code executed as the lateinit > call will not be able to disable it: > > if (__clk_is_enabled(clk) && clk->ops->disable) > clk->ops->disable(clk->hw); > > So I think we're quite safe with fixed rate clocks and fixed factor > clocks in that no-one can disable them :-) Hi Thomas I don't think we are taking about the same clock. I mean the gate clock: 28 ddr DDR Cntrl not the core clock. Andrew -- 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/