From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751730Ab3LLTji (ORCPT ); Thu, 12 Dec 2013 14:39:38 -0500 Received: from mail-pb0-f47.google.com ([209.85.160.47]:46749 "EHLO mail-pb0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751585Ab3LLTjf (ORCPT ); Thu, 12 Dec 2013 14:39:35 -0500 Message-ID: <52AA10F4.6070108@linaro.org> Date: Thu, 12 Dec 2013 11:39:32 -0800 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: Brecht Machiels , linux-kernel@vger.kernel.org Subject: Re: [REGRESSION] 41c7f74 rtc: Disable the alarm in the hardware (v2) References: <20131201220343.2285b12ee1c1e54252dc7dd9@mos6581.org> <529CF1D5. 6010406@linaro.org> <20131202211958.GE7380@pd.tnic> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/05/2013 03:51 AM, Brecht Machiels wrote: > On Mon, 02 Dec 2013 22:19:58 +0100, Borislav Petkov wrote: > >> On Mon, Dec 02, 2013 at 12:47:17PM -0800, John Stultz wrote: >>> Ok, sorry about this. I've been hoping we'd get some better insight >>> into what's actually happening on these strange BIOSes where disabling >>> the irq seems to cause it to scream (powering the system back on when >>> its shutdown), in the hopes of having a proper workaround. But despite >>> Borislav's efforts, he didn't seem to be able to root cause the issue. >> Right, this bug is too nasty - you could generate good random numbers >> just from how the hardware behaves. :) And I've been trying to make >> sense of what happens but I failed, as you know. :( >> >> I consider it a huge waste of time and efforts having to deal with such >> b0rked hardware instead of throwing it out of the window into the poring >> rain while it is still powered. >> >>> Borislav, could you double check this patch still works on your >>> hardware as well? >> Well, we have the patch in SLES11: >> >> http://kernel.opensuse.org/cgit/kernel/commit/?h=SLE11- > SP3&id=835398eb94dca7d55acd1a2628372e602ae3252a >> and it passed testing. >> >> From what I see below, your version is equivalent to the one above with >> the logic reversed so it should work. I'll still try to get that >> affected box and run your version on it but it'll take a while. > Hello John and Boris, > > Thank you for your quick response. And no need for an apology, I can > understand your frustration with the way some hardware behaves. > > I ran with John's patch for a couple of days, and it seems to work. > Curiously, the laptop did spontaneously boot the first time that I shut > it down with the patched kernel. I have no conclusive explanation for > this, but I have noticed that a manual power down is necessary after > booting with an unpatched kernel. Simply rebooting with a patched kernel > is not enough to stop the spontaneous boots. As far as I can remember, I > went directly from my custom kernel (with the v2 patch reverted) to a > kernel with your patch applied, so I'm not 100% convinced everything is > all right. I should say that I did experience some spontaneous boots when > running only Windows XP in the past, so there may be occasions where > drivers might not be able to help at all. Yea. It seems almost like the RTC_AIE bit is inverted in the hardware or something. > Thankfully, after other shutdowns/hibernates (about 6 in total) the > laptop never booted spontaneously. > > As for killing alarm functionality on the affected systems, I did some > quick tests. With the patched kernel, I can set the RTC alarm by echoing > to /sys/class/rtc/rtc0/wakealarm, and the machine will boot at the > specified time. I have also tried setting the RTC alarm, and then > disabling it again by echoing '0' to /sys/class/rtc/rtc0/wakealarm. While > this sets the alrm_time to five minutes in the future, alarm_IRQ is set > to 'no' and the machine does *not* boot spontaneously 5 minutes after > shutting down. So, all seems well, as far as I can see. Unfortunately, I > don't know enough about the RTC driver to draw any conclusions from this. Ok. Sounds like the patch works fairly well then. I'll go ahead and queue it for 3.14 and -stable. thanks -john