From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH] omap: fix clocksource_32k to start from zero Date: Fri, 19 Mar 2010 10:41:02 -0700 Message-ID: <87iq8sxl8x.fsf@deeprootsystems.com> References: <1269007534-9282-1-git-send-email-aaro.koskinen@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pv0-f174.google.com ([74.125.83.174]:62292 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751460Ab0CSRlG (ORCPT ); Fri, 19 Mar 2010 13:41:06 -0400 Received: by pva4 with SMTP id 4so1716719pva.19 for ; Fri, 19 Mar 2010 10:41:05 -0700 (PDT) In-Reply-To: <1269007534-9282-1-git-send-email-aaro.koskinen@nokia.com> (Aaro Koskinen's message of "Fri\, 19 Mar 2010 16\:05\:34 +0200") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Aaro Koskinen Cc: linux-omap@vger.kernel.org, tony@atomide.com Aaro Koskinen writes: > When the 32k sync timer is used for sched_clock(), it should count > time from the kernel boot (clocksource init) instead of the last HW > reset. Otherwise printk.time values will jump suddenly during the boot: > > [ 0.000000] calling omap2_clk_arch_init+0x0/0x138 @ 1 > [ 0.000000] initcall omap2_clk_arch_init+0x0/0x138 returned -22 after 0 usecs > [ 0.000000] initcall omap2_clk_arch_init+0x0/0x138 returned with error code -22 > [ 0.000000] calling omap_init_clocksource_32k+0x0/0x98 @ 1 > [ 508.697937] initcall omap_init_clocksource_32k+0x0/0x98 returned 0 after 0 usecs > [ 508.697967] calling omap_init_devices+0x0/0x38 @ 1 > [ 508.698425] initcall omap_init_devices+0x0/0x38 returned 0 after 0 usecs > > This will confuse tools such as scripts/bootgraph.pl. > > Signed-off-by: Aaro Koskinen > --- > > See also the thread in linux-kernel: > http://marc.info/?t=126893533300022&r=1&w=2 > > arch/arm/plat-omap/common.c | 14 +++++++++----- > 1 files changed, 9 insertions(+), 5 deletions(-) > > diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c > index 088c1a0..ce2ad10 100644 > --- a/arch/arm/plat-omap/common.c > +++ b/arch/arm/plat-omap/common.c > @@ -100,10 +100,12 @@ EXPORT_SYMBOL(omap_get_var_config); > > #include > > +static u32 offset_32k __read_mostly; > + I think you need a comment in the code here as well, something like the first sentence from the changelog, so readers of this code can make easy sense of the '- offset_32k'. Otherwise, Acked-by: Kevin Hilman