From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752020Ab3LLVQ7 (ORCPT ); Thu, 12 Dec 2013 16:16:59 -0500 Received: from mail-pb0-f53.google.com ([209.85.160.53]:33251 "EHLO mail-pb0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751745Ab3LLVQ6 (ORCPT ); Thu, 12 Dec 2013 16:16:58 -0500 Message-ID: <52AA27C7.3090206@linaro.org> Date: Thu, 12 Dec 2013 13:16:55 -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 , Borislav Petkov CC: 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> <52AA10F4.6070108@linaro.org> In-Reply-To: <52AA10F4.6070108@linaro.org> 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 12/12/2013 11:39 AM, John Stultz wrote: > 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. Brecht: Is it OK if I add to the patch: Tested-by: Brecht Machiels Borislav: I'd like to add your tested by too, if you've had the chance. thanks -john