Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965372AbcKDR6R convert rfc822-to-8bit (ORCPT ); Fri, 4 Nov 2016 13:58:17 -0400 Received: from smtprelay.synopsys.com ([198.182.47.9]:59329 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934840AbcKDR6P (ORCPT ); Fri, 4 Nov 2016 13:58:15 -0400 From: Alexey Brodkin To: Vineet Gupta CC: Noam Camus , "tglx@linutronix.de" , "linux-snps-arc@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Daniel Lezcano Subject: RE: [PATCH v2 01/10] ARC: timer: rtc: implement read loop in "C" vs. inline asm Thread-Topic: [PATCH v2 01/10] ARC: timer: rtc: implement read loop in "C" vs. inline asm Thread-Index: AQHSNhm2d4FQ1A8e+EiKaI2ei4jUeaDIVBDQ Date: Fri, 4 Nov 2016 17:58:11 +0000 Message-ID: <4881796E12491D4BB15146FE0209CE646785A901@DE02WEMBXB.internal.synopsys.com> References: <1478208701-30923-1-git-send-email-vgupta@synopsys.com> <1478208701-30923-2-git-send-email-vgupta@synopsys.com> In-Reply-To: <1478208701-30923-2-git-send-email-vgupta@synopsys.com> Accept-Language: en-US, ru-RU Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.13.178.24] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2032 Lines: 54 Hi Vineet, > -----Original Message----- > From: Vineet Gupta [mailto:vgupta@synopsys.com] > Sent: Friday, November 04, 2016 12:32 AM > To: Daniel Lezcano > Cc: Noam Camus ; tglx@linutronix.de; linux-snps-arc@lists.infradead.org; linux-kernel@vger.kernel.org; > Alexey.Brodkin@synopsys.com; Vineet Gupta ; stable@vger.kernel.org > Subject: [PATCH v2 01/10] ARC: timer: rtc: implement read loop in "C" vs. inline asm > > The current code doesn't even compile .... > > CC: stable@vger.kernel.org > Signed-off-by: Vineet Gupta > --- > arch/arc/kernel/time.c | 19 +++++++++++-------- > 1 file changed, 11 insertions(+), 8 deletions(-) > > diff --git a/arch/arc/kernel/time.c b/arch/arc/kernel/time.c > index f927b8dc6edd..1a117b999c0c 100644 > --- a/arch/arc/kernel/time.c > +++ b/arch/arc/kernel/time.c > @@ -152,14 +152,17 @@ static cycle_t arc_read_rtc(struct clocksource *cs) > cycle_t full; > } stamp; > > - > - __asm__ __volatile( > - "1: \n" > - " lr %0, [AUX_RTC_LOW] \n" > - " lr %1, [AUX_RTC_HIGH] \n" > - " lr %2, [AUX_RTC_CTRL] \n" > - " bbit0.nt %2, 31, 1b \n" > - : "=r" (stamp.low), "=r" (stamp.high), "=r" (status)); > + /* > + * hardware has an internal state machine which tracks readout of > + * low/high and updates the CTRL.status if > + * - interrupt/exception taken between the two reads > + * - high increments after low has been read > + */ > + do { > + stamp.low = read_aux_reg(AUX_RTC_LOW); > + stamp.high = read_aux_reg(AUX_RTC_HIGH); > + status = read_aux_reg(AUX_RTC_CTRL); > + } while (!(status & _BITUL(31))); I think original Daniel's comment was about constant value used here. Now with "_BITUL" it already looks much better but IMHO it would be even better if 31 gets converted here to something like: ------------------------>8-------------------- #define RTC_CTRL_A1_OFFSET 31 ------------------------>8-------------------- -Alexey