Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754950AbcDTMCY (ORCPT ); Wed, 20 Apr 2016 08:02:24 -0400 Received: from down.free-electrons.com ([37.187.137.238]:54675 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751751AbcDTMCX (ORCPT ); Wed, 20 Apr 2016 08:02:23 -0400 Date: Wed, 20 Apr 2016 14:02:21 +0200 From: Alexandre Belloni To: Anurag Kumar Vulisha Cc: Alessandro Zummo , Soren Brinkmann , Michal Simek , "rtc-linux@googlegroups.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Punnaiah Choudary Kalluri , Anirudha Sarangi , Srikanth Vemula , Srinivas Goud Subject: Re: [PATCH 3/3] RTC: Update seconds time programming logic Message-ID: <20160420120221.GR29844@piout.net> References: <1460463346-24923-1-git-send-email-anuragku@xilinx.com> <1460463346-24923-3-git-send-email-anuragku@xilinx.com> <20160419223109.GF29844@piout.net> <3802E9A6666DF54886E2B9CBF743BA9825E0B42B@XAP-PVEXMBX01.xlnx.xilinx.com> <20160420075741.GK29844@piout.net> <3802E9A6666DF54886E2B9CBF743BA9825E0B4BE@XAP-PVEXMBX01.xlnx.xilinx.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3802E9A6666DF54886E2B9CBF743BA9825E0B4BE@XAP-PVEXMBX01.xlnx.xilinx.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1862 Lines: 44 On 20/04/2016 at 10:31:06 +0000, Anurag Kumar Vulisha wrote : > > Yeas, I understood that. But my question was whether the interrupt handling > > was necessary at all. > > Instead of waiting for an interrupt to set time_updated, can't you simply read > > RTC_INT_STS and check for the RTC_INT_SEC bit in > > xlnx_rtc_read_time() ? > > > > Something like: > > > > status = readl(xrtcdev->reg_base + RTC_INT_STS) if (status & RTC_INT_SEC) > > rtc_time64_to_tm(readl(xrtcdev->reg_base + RTC_CUR_TM), tm); > > else > > rtc_time64_to_tm(readl(xrtcdev->reg_base + RTC_SET_TM_RD) - 1, > > tm); > > > > It all depends on whether the RTC_INT_SEC bit in RTC_INT_STS is being > > updated even when it is not enabled as an interrupt. > > > > The above said logic will work if we doesn't clear the RTC_INT_STS register after the > RTC_INT_SEC bit is set, this happens only if interrupts are not enabled. If interrupts > are enabled we will be clearing the RTC_INT_STS every time in the interrupt handler. > And moreover we need to return time from RTC_SET_TM_RD only if time is requested > within 1 sec span after programming the time only , so this is required only for one time. > Since we are clearing the RTC_INT_STS in our interrupt handler, we might end up in giving > the wrong time to the user when requested.So I think this logic might not work. > Please correct me if am wrong. > Simply stop clearing RTC_INT_SEC from RTC_INT_STS in the interrupt handler. You can also remove if (status & RTC_INT_SEC) rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_UF); as it will not be used. Update interrupts are handled by the core using timers anyway. And as you can see, there was no code enabling RTC_INT_SEC in RTC_INT_EN before your patch. -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com