Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753674Ab2JIH0g (ORCPT ); Tue, 9 Oct 2012 03:26:36 -0400 Received: from mga03.intel.com ([143.182.124.21]:30091 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753070Ab2JIH0d (ORCPT ); Tue, 9 Oct 2012 03:26:33 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,558,1344236400"; d="scan'208";a="202213116" Date: Tue, 9 Oct 2012 15:19:59 +0800 From: Feng Tang To: Jonathan Nieder Cc: Len Brown , "linux-acpi@vger.kernel.org" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Brown, Len" , "stable@vger.kernel.org" Subject: Re: [PATCH 27/30] ACPI: EC: Add a quirk for CLEVO M720T/M730T laptop Message-ID: <20121009151959.548d8718@feng-i7> In-Reply-To: <20121009065907.GB3648@elie.Belkin> References: <67bfa9b60bd689601554526d144b21d529f78a09.1349761836.git.len.brown@intel.com> <20121009061633.GA3648@elie.Belkin> <20121009142206.63dd9981@feng-i7> <20121009065907.GB3648@elie.Belkin> Organization: intel X-Mailer: Claws Mail 3.7.6 (GTK+ 2.22.0; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1936 Lines: 50 On Mon, 8 Oct 2012 23:59:07 -0700 Jonathan Nieder wrote: > Feng Tang wrote: > > Jonathan Nieder wrote: > > >> What would go wrong if the threshold were just increased to 20 on all > >> models? > > > > Then some other platform will stop to work. > > https://bugzilla.kernel.org/show_bug.cgi?id=11892 > > > > The 26/30 and 27/30 patches are bound together to fix one bug. Some > > quote from description from the 26th patch: > > > > ACPI_EC_STORM_THRESHOLD was initially 20 when it's created, and > > was changed to 8 in 2.6.28 commit 06cf7d3c7 "ACPI: EC: lower interrupt storm > > threshold" to fix kernel bug 11892 by forcing the laptop in that bug to > > work in polling mode. > > > > Hope this answers your question. > > Thanks much. Yes, that clarifies. > > The magic numbers are not too thrilling. If the polling mode just > doesn't work on the Clevo M720, why isn't the appropriate storm > threshold 999999 or infinity rather than 20? Do we know why the > polling mode doesn't work? I don't know why it doesn't work, if you check the https://bugzilla.kernel.org/show_bug.cgi?id=45151 you'll see the debugging model is test result --> patch --> 1-2 weeks + result --> patch --> 1-2 weeks + result ... over and over, which makes it difficult to root cause it but provide a workaround. And frankly speaking, I'm not sure if I can figure it out 100% even if I had that HW at hand. As per my understanding, EC is very tricky, as OS, ACPI FW, EC FW, BIOS will all access it without a global lock (in most cases), which makes it hard to work properly without race condition. Not mentioning its hardware may be broken. Thanks, Feng -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/