From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH V2 4/4] ARM: OMAP2+: AM43x: Use gptimer as clocksource Date: Fri, 28 Feb 2014 15:34:02 -0800 Message-ID: <20140228233402.GY13624@atomide.com> References: <1391768486-2134-1-git-send-email-lokeshvutla@ti.com> <1391768486-2134-5-git-send-email-lokeshvutla@ti.com> <20140213231919.GO28216@atomide.com> <52FDD7D5.30508@ti.com> <530B4391.2050205@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-03-ewr.mailhop.org ([204.13.248.66]:35981 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752139AbaB1XeP (ORCPT ); Fri, 28 Feb 2014 18:34:15 -0500 Content-Disposition: inline In-Reply-To: <530B4391.2050205@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Lokesh Vutla Cc: Rajendra Nayak , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, nm@ti.com, linux@arm.linux.org.uk, nsekhar@ti.com * Lokesh Vutla [140224 05:08]: > Hi Tony, > On Friday 14 February 2014 02:16 PM, Rajendra Nayak wrote: > > On Friday 14 February 2014 04:49 AM, Tony Lindgren wrote: > >> * Lokesh Vutla [140207 02:24]: > >>> From: Rajendra Nayak > >>> > >>> The SyncTimer in AM43x is clocked using the following two sources: > >>> 1) An inaccuarte 32k clock (CLK_32KHZ) derived from PER DPLL, causing system > >>> time to go slowly (~10% deviation). > >>> 2) external 32KHz RTC clock, which may not always be available on board like > >>> in the case of ePOS EVM > >>> > >>> Use gptimer as clocksource instead, as is done in the case of AM335x > >>> (which does not have a SyncTimer). With this, system time keeping works > >>> accurately. > >> > >> Hmm doesn't this also mean that PM for any deeper idle states won't > >> work properly? > > > > Thats true. This would mean we cannot put the peripheral/core domain down > > in idle. Suspend however can still work if suspend/resume callbacks are added > > to the clockevent and clocksource code to shut the non-wakeup domain timer. > This is a platform level limitation that only MPU domain can be put down in idle, just like AM335x. OK applying all four into omap-for-v3.15/soc thanks. Tony