From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [RFC] [PATCH 1/3] Allow to override the RTC alarm time Date: Thu, 10 Apr 2008 22:13:47 -0700 Message-ID: <200804102213.47756.david-b@pacbell.net> References: <1207722851.5997.16.camel@yakui_zhao.sh.intel.com> <200804090313.34805.david-b@pacbell.net> <1207825723.8704.26.camel@yakui_zhao.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp122.sbc.mail.sp1.yahoo.com ([69.147.64.95]:34348 "HELO smtp122.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750743AbYDKFNt (ORCPT ); Fri, 11 Apr 2008 01:13:49 -0400 In-Reply-To: <1207825723.8704.26.camel@yakui_zhao.sh.intel.com> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Zhao Yakui Cc: "Zhang, Rui" , linux-acpi@vger.kernel.org, lenb@kernel.org, Alessandro Zummo On Thursday 10 April 2008, Zhao Yakui wrote: > At the same time there is another question about this. > alm.enabled is related with AIE flag. When alarm is fired, the AIE fl= ag > won't be cleared automatically. Are you sure? I thought that bug was fixed... alarms should be one-shot, not periodic. > If we want to set alarm again, should we=20 > turn off the alarm firstly? =A0 As a rule, yes. We want to present a portable model for RTC alarms, which fire exactly once. The PC/AT model, with wildcarding for hh:mm:ss (and maybe MM:DD, allowed by ACPI extensions) is not very portable. (By the way, if someone wants to take rtc-cmos off my hands, I'd be glad to offload it ... my interest was just to try to get the PC platform to play in the same RTC space the other Linux platforms do!) > > That's a fair question. =A0I don't think there's a good answer > > to that with today's infrastructure. =A0Arguably, there should > > be the notion of a number of clients, each of which get told > > when the alarm they request fires. =A0But today, there's only > > a single alarm, and a single client. >=20 > Agree. Now there is only one alarm and current infrastruture can't > support more than two clients. I don't see how it could be claimed to support two clients. The second one clobbers the first ... Now, there *ARE* some RTCs that support multiple alarms. It's common in discrete I2C and SPI chips. But that's a capability that's not currently exposed by Linux; one of many, as noted in the current rtc(4) man page (dated 2006-11-26 in my copy). - Dave -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html