From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga17.intel.com ([192.55.52.151]:36862 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751254AbeDTF7h (ORCPT ); Fri, 20 Apr 2018 01:59:37 -0400 Message-ID: <1524203968.2553.32.camel@intel.com> Subject: Re: [PATCH 1/3] rtc: cmos: allow using ACPI for RTC alarm instead of HPET From: Zhang Rui To: Alexandre Belloni Cc: linux-pm@vger.kernel.org, linux-rtc@vger.kernel.org, rjw@rjwysocki.net, gabriele.mzt@gmail.com Date: Fri, 20 Apr 2018 13:59:28 +0800 In-Reply-To: <20180419140538.GG7369@piout.net> References: <1522072683-3968-1-git-send-email-rui.zhang@intel.com> <20180419140538.GG7369@piout.net> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-rtc-owner@vger.kernel.org List-ID: Hi, Alexandre On 四, 2018-04-19 at 16:05 +0200, Alexandre Belloni wrote: > Hi, > > > On 26/03/2018 21:58:01+0800, Zhang Rui wrote: > > > > It's found that the HPET timer prevents the platform from entering > > Low Power S0 on some new Intel platforms. > > > > This means that > > 1. users can still use RTC wake Alarm for suspend-to-idle, but the > > system > >    never enters Low Power S0, which is a waste of power. > > or > > 2. if users want to put the system into Low Power S0, they can not > > use > >    RTC as the wakeup source. > > > > To fix this, we need to stop using the HPET timer for wake alarm. > > But disabling CONFIG_HPET_EMULATE_RTC is not an option because HPET > > emulates PIT at the same time, and this is needed on some of these > > platforms. > > > > Thus, introduce a new mode (use_acpi_alarm) to the rtc_cmos driver, > > so that, even with CONFIG_HPET_EMULATE_RTC enabled, it's still > > possible to > > use ACPI SCI for RTC Alarm, including UIE/AIE/wkalrm, instead of > > HPET. > > > > Only necessary changes are made for the new "use_acpi_alarm" mode, > > including > > 1. drop all the calls to HPET emulation code, including the HPET > > irq > >    handler for rtc interrupt. > > 2. enabling/disabling ACPI RTC Fixed event upon RTC UIE/AIE > > request. > > 3. acknowledge the RTC Alarm in ACPI RTC Fixed event handler. > > > > There is no functional change made in this patch if the new mode is > > not > > enabled. > > > > Note: this "use_acpi_alarm" mode is made based on the assumption > > that > > ACPI RTC Fixed event is reliable both at runtime and during system > > wakeup. > > And this has been verified on a couple of platforms I have, > > including > > a MS Surface Pro 4 (SKL), a Lenovo Yoga 900 (SKL), and a HP 9360 > > (KBL). > > > > Signed-off-by: Zhang Rui > > --- > >  drivers/rtc/rtc-cmos.c | 111 +++++++++++++++++++++++++++++++++++ > > -------------- > >  1 file changed, 80 insertions(+), 31 deletions(-) > > > I've applied the series but it didn't apply cleanly, please check > https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git/lo > g/?h=rtc-next > Yes, I noticed this conflict as well. I have rebased it on top of -rc1 and it is under testing right now. I will rebase on your tree and resend. thanks, rui