From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755911Ab2KMWwW (ORCPT ); Tue, 13 Nov 2012 17:52:22 -0500 Received: from ogre.sisk.pl ([193.178.161.156]:41982 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754045Ab2KMWwU (ORCPT ); Tue, 13 Nov 2012 17:52:20 -0500 From: "Rafael J. Wysocki" To: "Moore, Robert" Cc: Mika Westerberg , "mathias.nyman@linux.intel.com" , "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "lenb@kernel.org" , "Wysocki, Rafael J" , "broonie@opensource.wolfsonmicro.com" , "grant.likely@secretlab.ca" , "linus.walleij@linaro.org" , "khali@linux-fr.org" , Bjorn Helgaas , "Zheng, Lv" Subject: Re: [PATCH 3/3] ACPI: Evaluate _CRS while creating device node objects Date: Tue, 13 Nov 2012 23:56:40 +0100 Message-ID: <1957831.MvUm7YPtfp@vostro.rjw.lan> User-Agent: KMail/4.8.5 (Linux/3.7.0-rc5; KDE/4.8.5; x86_64; ; ) In-Reply-To: <94F2FBAB4432B54E8AACC7DFDE6C92E346BC083A@ORSMSX101.amr.corp.intel.com> References: <1351928793-14375-1-git-send-email-mika.westerberg@linux.intel.com> <2586712.Jsv1H95qXQ@vostro.rjw.lan> <94F2FBAB4432B54E8AACC7DFDE6C92E346BC083A@ORSMSX101.amr.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, November 13, 2012 10:06:03 PM Moore, Robert wrote: > I may not quite understand what you are asking for, but I will try. > It seems like we already have much of what you want/need, so maybe > I'm missing something. I think all of the necessary pieces are there. > > So what I would like to have, in general terms, is something like > > acpi_walk_resources() split into three parts: > > > > (1) One that processes the _CRS output and creates a list of > > struct acpi_resource objects for us to play with. I suppose > > it's OK if that's just a buffer filled with resource objects, > > but a linked list might be more convenient. > > > > This sounds like AcpiGetCurrentResources. It executes _CRS and formats > the data into acpi_resource objects. Yes, it does. However, it is not completely clear to me if/how the caller is supposed to prepare the buffer object pointed to by the second arg. If the buffer is initialized by AcpiGetCurrentResources, then that's what I need for (1). > > (2) One that allows us to access (read/write) resources in the > > list returned by (1). We don't need to open code walking > > the list and I probably wouldn't event want to do that. What > > we need is to be able to walk the same list for a number of > > times and possibly to modify values in the resource objects > > if there are conflicts. > > This sounds like AcpiWalkResources. I suppose a possible issue is that > currently, AcpiWalkResources actually invokes the _CRS, _PRS, or _AEI > method on behalf of the caller. Yes, that exactly is the problem. > It might make more sense to allow the caller to pass in the resource buffer > returned from a call to _CRS, etc. Yes! :-) > > > > (3) One allowing us to free the list returned by (1) if not needed > > any more. > > > > AcpiGetCurrentResources: Currently, everything is returned in a single buffer > to minimize the number of allocations. A buffer you can free when you are > done with it. I suppose I should use ACPI_FREE(buffer.pointer) for that, but isn't it for the ACPICA's internal use only? Besides, I would prefer to be able to pass just "buffer" for freeing, without having to touch its internals. No big deal, but it would be nicer. :-) > I think I saw where you mentioned that you cannot copy this buffer because > of internal pointers to other areas of the buffer. Yes. However, we can build > linked lists all day if you really want them :-) I really won't care if I can pass a resource buffer to a "walker" routine. :-) > > And it would be great if we could take the list returned by (1), modify > > the resources in it and feed it back to _SRS (after conversion back to the > > format that _SRS understands). > > > > AcpiSetCurrentResources. > > The AML debugger already has a command that illustrates the use of the > various resource interfaces, see dbcmds.c I will. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.