From mboxrd@z Thu Jan 1 00:00:00 1970 From: Archit Taneja Subject: Re: [PATCH 2/2] ARM: OMAP4: DSS hwmods: Add OCPIF_SWSUP_IDLE to all DSS L3 slave interfaces Date: Fri, 13 Apr 2012 14:21:48 +0530 Message-ID: <4F87E924.5040601@ti.com> References: <1334304116-18872-1-git-send-email-archit@ti.com> <1334304116-18872-3-git-send-email-archit@ti.com> <4F87E72A.2050104@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:55809 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754645Ab2DMIwT (ORCPT ); Fri, 13 Apr 2012 04:52:19 -0400 In-Reply-To: <4F87E72A.2050104@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Cousson, Benoit" Cc: tomi.valkeinen@ti.com, paul@pwsan.com, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org On Friday 13 April 2012 02:13 PM, Cousson, Benoit wrote: > On 4/13/2012 10:01 AM, Archit Taneja wrote: >> The clock for all DSS L3 slave interfaces had been recently changed to >> "dss_fck" from "l3_div_ck". "dss_fck" is an optional clock in DSS >> clock domain >> which can't autoidle when enabled. >> >> Add OCPIF_SWSUP_IDLE flag to all the L3 slave interfaces used by DSS >> hwmods so >> that clock is explicitly enabled and disabled by software. Without this, >> "dss_fck" would be left as enabled and the OMAP4 device won't idle >> even when >> DSS is not in use. > > Yeah, that was done on purpose with Tomi knowning well that limitation. > > The issue was mainly due to the lack of proper parent / child > relationship between the DSS (the whole subsystem) and the DSS children > at that time. > > I think that Tomi posted a series to fix that for 3.4. So if we ensure > that every DSS IPs are children of the DSS, then pm_runtime will always > ensure that the DSS will be enabled each time a submodule is used. > > So the right fix is to put back the proper iclk (l3_div) to the DSS > instead of the dss_fck. Ok, I get it now. Tomi's patch series ensured the parent-child dependency, but they didn't switch the iclks back to l3_div, I guess that should be a part of the series too. Thanks, Archit > > The current OMAP4 DSS clock setup is clearly a hack that should be fixed. > > Regards, > Benoit >