From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752939AbcBHOGR (ORCPT ); Mon, 8 Feb 2016 09:06:17 -0500 Received: from down.free-electrons.com ([37.187.137.238]:37799 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750922AbcBHOGQ (ORCPT ); Mon, 8 Feb 2016 09:06:16 -0500 Date: Mon, 8 Feb 2016 15:06:14 +0100 From: Boris Brezillon To: Daniel Lezcano Cc: Nicolas Ferre , Romain Izard , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Thomas Gleixner , Alexandre Belloni Subject: Re: [PATCH v1] clocksource: atmel-pit: register as a sched_clock Message-ID: <20160208150614.5e87133e@bbrezillon> In-Reply-To: <56B89910.3060305@linaro.org> References: <1454606493-15094-1-git-send-email-romain.izard.pro@gmail.com> <56B89910.3060305@linaro.org> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.27; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org + Alexandre Hi Daniel, On Mon, 8 Feb 2016 14:33:04 +0100 Daniel Lezcano wrote: > On 02/04/2016 06:21 PM, Romain Izard wrote: > > Register the counter of the Periodic Interval Timer as a possible source > > for sched_clock. This provides a better precision than the jiffies-based > > default. > > > > Signed-off-by: Romain Izard > > Nicolas, Boris, > > Are you ok with this patch ? Not sure yet :). On most platforms we are also declaring a clocksource based on the TCB IP, and this one provides a better precision than the PIT clocksource. What happens if the PIT is de-activated while it's still supposed to provide the sched_clock(). Is there a way to flag the clocksource as still needed so that the core does not shut it down by when the TCB clocksource comes in. Best Regards, Boris -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com