From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753522AbZE3HfI (ORCPT ); Sat, 30 May 2009 03:35:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750939AbZE3He5 (ORCPT ); Sat, 30 May 2009 03:34:57 -0400 Received: from qw-out-2122.google.com ([74.125.92.27]:15018 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750787AbZE3He5 convert rfc822-to-8bit (ORCPT ); Sat, 30 May 2009 03:34:57 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=Y98XF1Y7j7Xa5tY6XqyqHQJt+8wORC6+rEoRqnl/GnKQ/9CuJzCihJPgwqcfJatWtV qszgBCKFo/gkJN2igk1uXtT3BAhdW+kIymP0rD2b6mQuKpn/jOXgPuYxCTlJOAazI1Gq rccRGJLqcaWVnz4ujCRPHgJsc+njuK96D3wTQ= MIME-Version: 1.0 In-Reply-To: <200905300135.07103.rjw@sisk.pl> References: <1241483224-7113-1-git-send-email-khilman@deeprootsystems.com> <200905232214.57186.rjw@sisk.pl> <4A1A4297.50809@samsung.com> <200905300135.07103.rjw@sisk.pl> From: Kim Kyuwon Date: Sat, 30 May 2009 16:34:38 +0900 Message-ID: <4d34a0a70905300034q1dee8febl60b5213082e3a5d1@mail.gmail.com> Subject: Re: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs To: "Rafael J. Wysocki" Cc: Kim Kyuwon , Andrew Morton , linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Ingo Molnar , Kyungmin Park , Linus Torvalds , Kevin Hilman Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 30, 2009 at 8:35 AM, Rafael J. Wysocki wrote: > On Monday 25 May 2009, Kim Kyuwon wrote: >> Rafael J. Wysocki wrote: >> > On Saturday 23 May 2009, Kim Kyuwon wrote: >> >> On Sat, May 23, 2009 at 7:29 AM, Rafael J. Wysocki wrote: >> >>> On Saturday 23 May 2009, Kim Kyuwon wrote: >> > [--snip--] >> >>>> You changed the really important part of Linux, which may affect most >> >>>> processor architectures. I think you should be careful. If some of >> >>>> architectures can't take care of it (they can implement >> >>>> disable_irq_wake correctly in H/W level, will you revert your changes? >> >>> No, the changes are not going to be reverted.  In fact things should have been >> >>> done like this already much earlier. >> >>> >> >>> Now, do you have any particular example of a problem related to these changes >> >>> or is it only a theoretical issue? >> >> I'd CCing you when I'm sending a mail for this particular example of a example. >> >> http://markmail.org/thread/fvt7d62arofon5xx >> > >> > Well, as I said above, reverting the changes that introduced >> > [suspend|resume]_device_irqs() is not an option, becuase it was the only sane >> > way to achieve the goal they were added for.  So, we need to fix the wake-up >> > problem on your platform with the assumption that >> > [suspend|resume]_device_irqs() are going to stay. >> > >> > For starters, would it be possible to teach the 'disable' hook of your >> > platform's interrupt controller not to mask the IRQs that have both >> > IRQ_WAKEUP and IRQ_SUSPENDED set?  That apparently would work around the >> > wake-up interrupts problem. >> >> Thank you for considering this issue and spending your time. In order to >> make your idea work, we need to add a dummy 'set_wake' hook which >> returns always zero. Anyway, IMO, I think your idea is good to work >> around this problem. But Kevin Hilman(OMAP PM Maintainer) would make >> final decision. >> >> Buy the way, how can you handle the problem that a few interrupt are >> discarded in a small window? I can be sure they are discarded, because I >> have debugged defects which generate in sleep/resume state hundreds of >> times on ARM Processors(PXA310, S3C6410, OMAP3430). Wake-up interrupts >> are generated as soon as arch_suspend_enable_irqs() invoked. > > Sorry for the delayed response. > > If the wake-up interrupts are not masked, they will be delivered to the drivers > as soon as arch_suspend_enable_irqs() has run.  So, if the drivers are able to > handle them at this point (ie. before resume_device_irqs() is called), they > won't be lost. Thank you for your response! Your suspend_device_irqs() disables all IRQs(except timer IRQ) while entering suspend. i.e. Before invoking resume_device_irqs() or resume_noirq callback, all IRQs(except timer IRQ) is in IRQ_DISABLED status. Right? But if an IRQ is in IRQ_DISABLED status, its interrupt handler can be invoked. (As you know, all IRQs with IRQ_DISABLE are not handled in handle_level_irq function). Thus, even if the wake-up interrupts are not masked, the drivers are not able to handle interrupts, because the interrupt handler can't be invoked due to IRQ_DISABLED set by suspend_device_irqs(). > The only problem I see is that the drivers may expect their > ->resume_noirq() callbacks to be executed first. resume_noirq() callbacks are also invoked after arch_suspend_enable_irqs(). Regards, Kyuwon