Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755041Ab3DVKtZ (ORCPT ); Mon, 22 Apr 2013 06:49:25 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:57333 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307Ab3DVKtX (ORCPT ); Mon, 22 Apr 2013 06:49:23 -0400 Date: Mon, 22 Apr 2013 11:48:58 +0100 From: Will Deacon To: Stephen Boyd Cc: Rob Herring , "linux-kernel@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Russell King , "arm@kernel.org" , Catalin Marinas , John Stultz , Thomas Gleixner Subject: Re: [PATCH 3/4] ARM: sched_clock: Add support for >32 bit sched_clock Message-ID: <20130422104858.GB2572@mudshark.cambridge.arm.com> References: <1366417746-24990-1-git-send-email-sboyd@codeaurora.org> <1366417746-24990-4-git-send-email-sboyd@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1366417746-24990-4-git-send-email-sboyd@codeaurora.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 Content-Length: 1683 Lines: 41 Hi Stephen, On Sat, Apr 20, 2013 at 01:29:05AM +0100, Stephen Boyd wrote: > The arm architected system counter has at least 56 bits of > useable bits. Add support to ARM's sched_clock implementation for > counters with more than 32 bits so we can avoid the complexity of > dealing with wraparound on these devices while benefiting from > the irqtime accounting and suspend/resume handling that the ARM > sched_clock code already has. > > Signed-off-by: Stephen Boyd > --- > > Maybe we need a union for the epoch_ns usage? > > arch/arm/include/asm/sched_clock.h | 2 + > arch/arm/kernel/sched_clock.c | 101 +++++++++++++++++++++++++++---------- > 2 files changed, 77 insertions(+), 26 deletions(-) > > diff --git a/arch/arm/include/asm/sched_clock.h b/arch/arm/include/asm/sched_clock.h > index 3d520dd..7fcd2ee 100644 > --- a/arch/arm/include/asm/sched_clock.h > +++ b/arch/arm/include/asm/sched_clock.h > @@ -13,4 +13,6 @@ extern void setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate); > > extern unsigned long long (*sched_clock_func)(void); > > +extern void setup_sched_clock_64(u64 (*read)(void), int bits, > + unsigned long rate); Curious, but why do we need two setup_sched_clock functions, where the bits are passed as a parameter? Can't we just do the right thing if the clock claims to be more than 32 bits wide (and get rid of the BUG_ONs at the same time)? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/