From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Stone Subject: Re: [PATCH v2 4/6] ACPI: ARM: exclude DMI calls Date: Mon, 25 Nov 2013 11:01:08 -0700 Message-ID: <52939064.6090803@linaro.org> References: <1385080915-23430-1-git-send-email-al.stone@linaro.org> <528F9C65.7010302@linaro.org> <4285284.l8TssFvumi@vostro.rjw.lan> <528FF15C.4060300@linaro.org> <20131123163854.GA1817@srcf.ucam.org> <1AE640813FDE7649BE1B193DEA596E880248D1A8@SHSMSX101.ccr.corp.intel.com> <20131125153016.GA3243@srcf.ucam.org> <52938C3F.20905@linaro.org> <20131125174552.GA7417@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ie0-f181.google.com ([209.85.223.181]:57485 "EHLO mail-ie0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754949Ab3KYSBK (ORCPT ); Mon, 25 Nov 2013 13:01:10 -0500 Received: by mail-ie0-f181.google.com with SMTP id e14so7344374iej.40 for ; Mon, 25 Nov 2013 10:01:09 -0800 (PST) In-Reply-To: <20131125174552.GA7417@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett Cc: "Zheng, Lv" , "Rafael J. Wysocki" , Olof Johansson , Rob Herring , "linux-acpi@vger.kernel.org" , Linaro Patches , "linaro-kernel@lists.linaro.org" , "linaro-acpi@lists.linaro.org" On 11/25/2013 10:45 AM, Matthew Garrett wrote: > On Mon, Nov 25, 2013 at 10:43:27AM -0700, Al Stone wrote: >> On 11/25/2013 08:30 AM, Matthew Garrett wrote: >>> Is ACPI_REDUCED_HARDWARE supposed to indicate support for the reduced >>> hardware profile, or that the platform *only* implements the reduced >>> hardware profile? >> >> From what I can see in ACPICA, ACPI_REDUCED_HARDWARE indicates the >> platform *only* implements the reduced hardware profile. This *seems* >> to be consistent with the specification -- see 3.11.1, second bullet, >> for example: > > Ok, so a kernel built without ACPI_REDUCED_HARDWARE would still support > the reduced hardware profile? Let me check on that. The reduced hardware profile is a pretty strict subset, and I think I can see a way where I could force selecting the reduced HW profile on boot if the kernel has been built *without* ACPI_REDUCED_HARDWARE. What I am not convinced of is that all of the proper guards are in place in ACPICA -- I trust that they have been, but I would like to double check. If I can get that to work properly, I'll add it to this patch set. >> ...if by "not supported" one takes that to mean "does not exist when >> compiled." I can look at the ACPICA code again, just the same; perhaps >> there is some reasonable way to at least select one or the other at boot >> as the first step, and then allow switching between modes as a later >> step. > > I don't think you'd ever want to switch after init time. There's a flag > in the FADT that indicates whether a system is implementing the reduced > hardware profile or not. > Agreed. I could see it as something to use when experimenting perhaps, but I think just allowing the switch at boot would cover the majority of the use cases. -- ciao, al ----------------------------------- Al Stone Software Engineer Linaro Enterprise Group al.stone@linaro.org -----------------------------------