From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Renninger Subject: Re: [PATCH] ACPI: Make Embedded Controller command timeout delay configurable Date: Mon, 25 Oct 2010 00:34:50 +0200 Message-ID: <201010250034.51170.trenn@suse.de> References: <201010211824.57893.trenn@suse.de> <201010230046.06637.trenn@suse.de> <201010230143.24858.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from cantor.suse.de ([195.135.220.2]:55220 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752374Ab0JXWes (ORCPT ); Sun, 24 Oct 2010 18:34:48 -0400 In-Reply-To: <201010230143.24858.rjw@sisk.pl> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: Len Brown , linux-acpi@vger.kernel.org On Saturday 23 October 2010 01:43:24 am Rafael J. Wysocki wrote: > On Saturday, October 23, 2010, Thomas Renninger wrote: > > On Friday 22 October 2010 11:22:00 pm Rafael J. Wysocki wrote: > > > On Friday, October 22, 2010, Len Brown wrote: > > > > applied > > > > > > OK > > > > > > What if I do ec_delay=0 ? > > Same as with quite some other boot params: > > Your machine won't boot. > > > > Why should this be a problem? > > Because your intention is to allow the users to _increase_ the delay and not > to decrease it. Decreasing it is known dangerous, so why don't you simply > put a limit in there? > > I know there are many boot params that will hurt you if not used with care, > but is that a sufficient reason for adding another one? To be honest I have not thought about the debug aspect of this param when I sent it. But I think Len is right and this can be used as a nice debug param to test whether there are EC accesses that take really long. For example you have the requirement that your EC provides data for all requests in X ms. You boot acpi.ec_delay=X and if there are timeout complaints you can then have a look at your EC firmware or at the kernel/ACPI code what the reasons were that things timed out. Nobody will decrease the limit, unless he wants to examine above problems. I can write kernel-parameters documentation, but I expect people finding this had a look at the code. If people see AE_TIME messages with a too low value, they should know that it obviously was the boot param they added and they can simply remove it again. Thomas