Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758795Ab3GRLCk (ORCPT ); Thu, 18 Jul 2013 07:02:40 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:32889 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758771Ab3GRLCf (ORCPT ); Thu, 18 Jul 2013 07:02:35 -0400 Date: Thu, 18 Jul 2013 12:02:01 +0100 From: Mark Rutland To: Jonas Jensen Cc: "linux-arm-kernel@lists.infradead.org" , "arm@kernel.org" , "mturquette@linaro.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3] clk: add MOXA ART SoCs clock driver Message-ID: <20130718110201.GB29153@e106331-lin.cambridge.arm.com> References: <1372943292-6960-1-git-send-email-jonas.jensen@gmail.com> <1374067396-30155-1-git-send-email-jonas.jensen@gmail.com> <20130718095035.GA29153@e106331-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Thread-Topic: [PATCH v3] clk: add MOXA ART SoCs clock driver Accept-Language: en-GB, en-US Content-Language: en-US User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1955 Lines: 52 On Thu, Jul 18, 2013 at 11:36:40AM +0100, Jonas Jensen wrote: > Hi Mark, thanks for taking a look at this. > > On 18 July 2013 11:50, Mark Rutland wrote: > > This confuses me. moxart_of_clk_init gets called because there was a > > "moxa,moxart-core-clock", node in the dt, but the driver only seems to > > use the information to figure out the configuration of another clock > > ("moxa,moxart-apb-clock"), and never registers a clock specifically for > > the core-clock. > > > > I couldn't find "moxa,moxart-apb-clock" described in mainline. COuld you > > describe the relationship between core-clock and apb-clock? > > It's true core-clock exist only so the register can be mapped. Ok. I'm just concerned that the linkage isn't explicit or obvious. > > apb-clock is part of a patch set that will add new device tree files for the > MOXA ART SoC, but it's not in mainline: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2013-July/181757.html > > apb-clock could be a fixed rate 48MHz DT only clock, but because we can't > be sure it's 48MHz on all platforms, reading it from a register with core-clock > is more portable. This does leave apb-clock completely dependent on core-clock, and unless I've missed something there's no linkage between the two described in the dt. How does core-clock physically relate to apb-clock? Does it feed or is it fed by apb-clock? Are we always guaranteed to have core-clock if we have apb-clock, and is it part of the same block in hardware? If so we could describe the amalgamation as a provider with two clock outputs, with core-clock's registers for configuration at probe-time. Thanks, Mark. > > > Best regards, > Jonas > -- 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/