From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Cousson, Benoit" Subject: Re: Problem with DSS clocks & accessing registers Date: Mon, 7 Mar 2011 15:52:35 +0100 Message-ID: <4D74F133.5020101@ti.com> References: <1299486149.2281.77.camel@deskari> <4D74E2D5.2000705@ti.com> <90dc32aa0eb6d68d2a56424de664653d@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from comal.ext.ti.com ([198.47.26.152]:36931 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751366Ab1CGOwk (ORCPT ); Mon, 7 Mar 2011 09:52:40 -0500 In-Reply-To: <90dc32aa0eb6d68d2a56424de664653d@mail.gmail.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Shilimkar, Santosh" Cc: "Valkeinen, Tomi" , "Nayak, Rajendra" , "Semwal, Sumit" , Paul Walmsley , "Hilman, Kevin" , linux-omap , "Taneja, Archit" On 3/7/2011 3:05 PM, Shilimkar, Santosh wrote: >> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap- >> owner@vger.kernel.org] On Behalf Of Cousson, Benoit >> >> + Rajendra >> >> Hi Tomi, >> >> On 3/7/2011 9:22 AM, Valkeinen, Tomi wrote: >>> Hi Kevin, Paul, >>> >>> We currently have a small problem with OMAP4 DSS. When we enable >> the DSS >>> clocks, it seems that the DSS registers are not always accessible >> right >>> after the clock enable. >> >> What clocks are you talking about? As you know, the DSS has a bunch >> of functional clocks available depending of the use case. >> >>> I understood that on OMAP4 the clock framework doesn't guarantee >> that >>> the registers are accessible after enabling clocks, and pm_runtime >> will handle this. Is this correct? >> > > This seems to the question about a so called optional clock (DSS_CLK) > which really not an optional clock :) > This clock needs to be enabled and disabled along with interface and > functional clock for the registers access to work. To be more accurate, this clock is one of the functional clock available for the DSS (the other being the SYS_CLK). You can use dss_clk or sys_clk (through dsi pll) to generate the functional clock of the DSS. The issue, as I said is that the availability status of the DSS is bound to the DSS module mode, not to any of this DSS clock. Benoit