From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suravee Suthikulpanit Subject: Re: [V8 PATCH 1/3] ACPICA: Add ACPI _CLS processing Date: Fri, 24 Apr 2015 16:08:31 -0500 Message-ID: <553AB0CF.1010904@amd.com> References: <1427752579-19234-1-git-send-email-Suravee.Suthikulpanit@amd.com> <1427752579-19234-2-git-send-email-Suravee.Suthikulpanit@amd.com> <1AE640813FDE7649BE1B193DEA596E8802704682@SHSMSX101.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-bl2on0129.outbound.protection.outlook.com ([65.55.169.129]:8154 "EHLO na01-bl2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965580AbbDXVIo (ORCPT ); Fri, 24 Apr 2015 17:08:44 -0400 In-Reply-To: <1AE640813FDE7649BE1B193DEA596E8802704682@SHSMSX101.ccr.corp.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Zheng, Lv" , "rjw@rjwysocki.net" , "mika.westerberg@linux.intel.com" , "Moore, Robert" , "hanjun.guo@linaro.org" Cc: "lenb@kernel.org" , "hdegoede@redhat.com" , "tj@kernel.org" , "mjg59@srcf.ucam.org" , "gregkh@linuxfoundation.org" , "al.stone@linaro.org" , "graeme.gregory@linaro.org" , "leo.duran@amd.com" , "linux-ide@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linaro-acpi@lists.linaro.org" On 4/16/15 20:45, Zheng, Lv wrote: > Before back porting this to ACPICA, let me ask one simple question. > According to the spec, the _CLS is optional and PCI specific. > So why should we implement it in ACPICA core not OSPM specific modules? > If this need to be implemented in ACPICA, then what about the following device identification objects? > _DDN, _HRV, _MLS, _PLD, _STR, _SUN > > Thanks and best regards > -Lv Hi, Sorry for late reply. As for the justification for introducing the _CLS support in the ACPICA, this is mainly because ACPI does not currently define _CID for certain device classes, which used to mostly be PCI devices. Instead, ACPI spec mentioned that _CLS can be used for loading generic drivers on hardware that is compatible with PCI-defined device classes, but that is not implemented on the PCI bus (and is therefore enumerated by ACPI.) The code introduced for supporting _CLS is also similar in the way ACPICA is currently parsing the _CID or _SUB (which are also optional), and using it for the same purpose of identifying devices for loading drivers. Also, since this method for identifying devices is OS-independent, I believe this should not be done in the OSPM specific modules. Thanks, Suravee