From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomi Valkeinen Subject: Re: [PATCH] video: omap2: dss: RET on idle, enable/disable dss clocks only when needed. Date: Mon, 21 Sep 2009 09:26:48 +0300 Message-ID: <1253514408.4690.5.camel@tubuntu> References: <1253230586-931-1-git-send-email-mike@android.com> <1253262472.28956.10.camel@tubuntu> <8bb80c380909181033s2fd5e3a1o16404f1667760b25@mail.gmail.com> Reply-To: tomi.valkeinen@nokia.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.nokia.com ([192.100.105.134]:23426 "EHLO mgw-mx09.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752200AbZIUG06 (ORCPT ); Mon, 21 Sep 2009 02:26:58 -0400 In-Reply-To: <8bb80c380909181033s2fd5e3a1o16404f1667760b25@mail.gmail.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: ext Mike Chan Cc: "linux-omap@vger.kernel.org" Hi, On Fri, 2009-09-18 at 19:33 +0200, ext Mike Chan wrote: > On Fri, Sep 18, 2009 at 1:27 AM, Tomi Valkeinen > wrote: > > Hi, > > > > If you disable the clocks to allow RET, you also allow OFF mode. And > > resuming from OFF mode hasn't been implemented for DSI, if I recall > > right. And when I was testing it, it didn't seem to be trivial with the > > DSI PLL. > > > > You can limiting the pwrdm next state to RET when being called from cpuidle. No, you _must_ limit it to RET. Otherwise the DSI will break down. So we can either keep the dsi code as it is now, or explicitely disable OFF mode and then apply your patch. But your patch alone won't work. In the long run I think we anyway need to somehow dynamically manage the power state. I haven't measured it but I believe resuming from OFF will have a bit of a penalty, as (I think) DSI PLL etc. will have to reinitialized. But it would still be good to allow RET whenever possible, and OFF only after some period of inactivity. Tomi