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 10:43:27 -0700 Message-ID: <52938C3F.20905@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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ie0-f171.google.com ([209.85.223.171]:39317 "EHLO mail-ie0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754455Ab3KYRna (ORCPT ); Mon, 25 Nov 2013 12:43:30 -0500 Received: by mail-ie0-f171.google.com with SMTP id ar20so7262898iec.2 for ; Mon, 25 Nov 2013 09:43:29 -0800 (PST) In-Reply-To: <20131125153016.GA3243@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett , "Zheng, Lv" Cc: "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 08:30 AM, Matthew Garrett wrote: > On Mon, Nov 25, 2013 at 05:10:46AM +0000, Zheng, Lv wrote: >>> From: linux-acpi-owner@vger.kernel.org [mailto:linux-acpi-owner@vger.kernel.org] On Behalf Of Matthew Garrett >>> Ugh. Really? People have been fairly careful about making sure that the >>> x86 SoC code is selected correctly at runtime, and losing that because >>> ACPICA is broken would be a shame. I think this is something that needs >>> to support runtime switching even if there's also support for building >>> kernels that only implement the reduced hardware profile. >> >> If my reading is correct, do you mean x86 SoCs should have already tested the code. > > I don't know if anyone has deployed x86 SoCs with reduced hardware yet, > but it seems like something that might happen. > >> So if ARM need ACPI_REDUCED_HARDWARE to be defined, the should have lines like: >> #ifdef CONFIG_ARCH_IS_ACPI_REDUCED_HARDWARE >> #define ACPI_REDUCED_HARDWARE TRUE >> #endif >> And ARCH_IS_ACPI_REDUCED_HARDWARE should only be selected by CONFIG_ARM. > > 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: Boot in ACPI mode only (ACPI Enable, ACPI Disable, SMI_CMD and Legacy mode are not supported) ...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. To Lv's point, since hardware reduced mode was added in ACPI 5.0, I don't think there has been a lot of exposure to it, especially on working platforms on the Linux side, so I doubt there has been any significant Linux testing of it until now. -- ciao, al ----------------------------------- Al Stone Software Engineer Linaro Enterprise Group al.stone@linaro.org -----------------------------------