From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967476Ab3E3Fcn (ORCPT ); Thu, 30 May 2013 01:32:43 -0400 Received: from guitar.tcltek.co.il ([192.115.133.116]:36355 "EHLO sivan.tkos.co.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751465Ab3E3Fci (ORCPT ); Thu, 30 May 2013 01:32:38 -0400 Date: Thu, 30 May 2013 08:32:33 +0300 From: Baruch Siach To: John Stultz Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Jamie Iles , Dinh Nguyen Subject: Re: [RFC PATCH 2/2] clocksource: dw_apb: allow build for architectures other than arm Message-ID: <20130530053233.GL25186@sapphire.tkos.co.il> References: <1369570367-994-2-git-send-email-baruch@tkos.co.il> <51A51271.2070506@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51A51271.2070506@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi John, On Tue, May 28, 2013 at 01:24:17PM -0700, John Stultz wrote: > On 05/26/2013 05:12 AM, Baruch Siach wrote: > >ARM is the only architecture providing sched_clock.h and setup_sched_clock(). > >Implement sched_clock() for use by other architectures. > > > >Cc: Ingo Molnar > >Cc: Peter Zijlstra > >Cc: John Stultz > >Cc: Thomas Gleixner > >Cc: Jamie Iles > >Cc: Dinh Nguyen > >Signed-off-by: Baruch Siach > >--- [snip] > >@@ -73,6 +77,9 @@ static void add_clocksource(struct device_node > > *source_timer) > > } > > static void __iomem *sched_io_base; > >+#ifndef CONFIG_HAVE_SETUP_SCHED_CLOCK > >+static u64 sched_clock_mult __read_mostly; > >+#endif > > static u32 read_sched_clock(void) > > { > >@@ -97,7 +104,11 @@ static void init_sched_clock(void) > > timer_get_base_and_rate(sched_timer, &sched_io_base, &rate); > > of_node_put(sched_timer); > >+#ifdef CONFIG_HAVE_SETUP_SCHED_CLOCK > > setup_sched_clock(read_sched_clock, 32, rate); > >+#else > >+ sched_clock_mult = NSEC_PER_SEC / rate; > >+#endif > > } > > Can you rework this to not use #ifdefs within the function? They > make it annoying to read the code. > > Instead maybe have a local setup_sched_clock() function that sets > the mult value for the !CONFIG_HAVE_SETUP_SCHED_CLOCK case? > > > static const struct of_device_id osctimer_ids[] __initconst = { > >@@ -124,3 +135,10 @@ void __init dw_apb_timer_init(void) > > init_sched_clock(); > > } > >+ > >+#ifndef CONFIG_HAVE_SETUP_SCHED_CLOCK > >+unsigned long long notrace sched_clock() > >+{ > >+ return read_sched_clock() * sched_clock_mult; > >+} > >+#endif > > Also, can you try to condense the number of #ifndef > CONFIG_HAVE_SETUP_SCHED_CLOCK checks to one, and consolidate the > needed functions all in that one conditional? Thanks for your comments. I'll rework the patch and resubmit. I've just noticed that I have a bigger problem. read_sched_clock() returns u32, not u64. This means that in a rate of, say, 100MHz it will wrap around after a little more than 40 seconds. Would it make sense to put ARM's 32 bin sched_clock extension code (arch/arm/kernel/sched_clock.c) is a common place (maybe drivers/clocksource), and use that? There seems to be nothing ARM specific in this code, after all. baruch -- http://baruch.siach.name/blog/ ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - baruch@tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -