Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754252Ab3JaNAJ (ORCPT ); Thu, 31 Oct 2013 09:00:09 -0400 Received: from mail-ie0-f176.google.com ([209.85.223.176]:65488 "EHLO mail-ie0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753508Ab3JaNAG (ORCPT ); Thu, 31 Oct 2013 09:00:06 -0400 Date: Thu, 31 Oct 2013 07:00:02 -0600 From: Bjorn Helgaas To: Lan Tianyu Cc: Tony Luck , Len Brown , "Rafael J. Wysocki" , Yinghai Lu , "linux-ia64@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "Yoknis, Mike" , "Pearson, Greg" Subject: Re: [Resend PATCH 5/5] IA64/PCI/ACPI: Rework PCI root bridge ACPI resource conversion Message-ID: <20131031130002.GA9862@google.com> References: <20131016235541.GD17866@google.com> <525F7F0F.5010306@intel.com> <52612D1C.4070701@intel.com> <20131023223904.GA18454@google.com> <526BF37E.8040801@intel.com> <5270C47C.5040206@intel.com> <5271BFBB.8040307@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5271BFBB.8040307@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5410 Lines: 144 On Thu, Oct 31, 2013 at 10:26:03AM +0800, Lan Tianyu wrote: > On 2013年10月31日 00:23, Bjorn Helgaas wrote: > > On Wed, Oct 30, 2013 at 2:34 AM, Lan Tianyu wrote: > >> On 2013年10月29日 01:32, Bjorn Helgaas wrote: > >>> > >>> On Sat, Oct 26, 2013 at 10:53 AM, Lan Tianyu wrote: > >>>> > >>>> On 10/24/2013 06:39 AM, Bjorn Helgaas wrote: > >>>>> > >>>>> On Fri, Oct 18, 2013 at 08:44:12PM +0800, Lan Tianyu wrote: > >>>>>> > >>>>>> > >>>>>> On 10/18/2013 04:33 AM, Bjorn Helgaas wrote: > >>> > >>> > >>>>>>> I wonder if it would make sense to make > >>>>>>> acpi_dev_resource_address_space() ignore addr.translation_offset for > >>>>>>> IO resources. Or maybe ignore it if the _TTP (type translation) bit > >>>>>>> is set? > >>>>>> > >>>>>> > >>>>>> > >>>>>> I wonder why current code doesn't check _TTP? The code in the > >>>>>> add_io_space() seems to think _TTP is always set, right? > >>>>> > >>>>> > >>>>> I think it's an oversight, and you should fix it. I suggest that you > >>>>> ignore the _TRA value when _TTP is set. Obviously this only applies > >>>>> to I/O port resources, since _TTP is only defined in the I/O Resource > >>>>> Flag (Table 6-185 in ACPI 5.0 spec). > >>>> > >>>> > >>>> _TTP is also defined in the Memory Resource flag, Please have a look at > >>>> Table 6-184 in the ACPI 5.0 Spec. > >>> > >>> > >>> Yes, you're right. That would be for a host bridge that converts I/O > >>> on the primary (upstream) side of the bridge to memory on the PCI > >>> side. I've never seen such a bridge, and I can't really imagine why > >>> anybody would do that. But I guess you should be able to safely > >>> ignore _TRA when _TTP is set in either a MEM or IO descriptor, because > >>> the same reasoning should apply to both. > >>> > >>>> I am not sure how to deal with _TTP unsetting io resource? _TTP unsetting > >>>> mean the resource is IO on the primary side and also IO on the secondary > >>>> side. > >>> > >>> > >>> If _TTP is not set, I guess you would apply _TRA. That's what you > >>> already do for MEM descriptors, and think you should just do the same > >>> for IO descriptors. I would guess that having _TTP = 0 and _TRA != 0 > >>> is rare for IO descriptors, but I suppose it could happen. > >> > >> > >> Yes, my concern is for the IO resource case of _TTP=0 and _TRA !=0. The > >> only reason for this case I think of is that the IO resource offsets on > >> the prime bus and second bus are different. In this case, we still need > >> to pass _TRA to new_space() and the finial resource->start still should be > >> acpi_resource->min + offset returned by add_io_space(), right? > > > > No, I don't think so. If the "phys_base" argument to new_space() is > > non-zero, it is the base of an MMIO region that needs to be > > ioremapped. This is handling the _TTP=1 case, where the MMIO region > > is translated by the bridge into an IO region on PCI. > > > > If _TTP=0, the region is IO on both the upstream and downstream sides > > of the host bridge, and we don't want to ioremap a new MMIO region for > > it. It might be part of the "legacy I/O port space," but that's > > already covered elsewhere. > > > > I don't think we need to add special handling for the _TTP=0 and _TRA > > != 0 case because I don't think it exists in the field. If and when > > it *does* exist, we'll know what to do. In the meantime, it should > > look just like the MEM path. > > > OK. I get it. acpi_dev_resource_address_space() will only apply _TRA to > resource ->start and ->end for both mem and io resource when _TTP=0. In > the add_window(), the offset returned by add_io_space() will be added > directly to ->start and ->end. > > add_window() { > ... > if (resource->flags & IORESOURCE_MEM) { > root = &iomem_resource; > offset = addr.translation_offset; I can wait for your patch to see the whole thing, but I would expect "offset = 0" here. For MEM resources, the arch code should not need to look inside "addr" at all. > } else if (resource->flags & IORESOURCE_IO) { > root = &ioport_resource; > > offset = add_io_space(info, &addr); > if (offset == ~0) > return AE_OK; > > resource->start += offset; > resource->end += offset; > } else > return AE_OK; > > ... > } > > > > >> If yes, I think _TRA can't be applied to IO resource in the > >> acpi_dev_resource_address_space() regardless of the value of _TTP. > >> > >> BTW, Translation Sparse(_TRS) is only meaningful if _TTP is set.(Table > >> 6-185). The add_io_space() doesn't check _TTP when set sparse. So this > >> should be corrected? > > > > Sure, I'm OK with this. It's possible we could trip over a BIOS bug > > where _TRS=1 but _TTP=0, but I think the risk is low because only > > large ia64 boxes would use this, and there aren't very many of those. > > > > Ok. I will add a check for _TTP before setting sparse. Something likes this. > > add_io_space() > { > ... > if (addr->info.io.translation == ACPI_TYPE_TRANSLATION && > addr->info.io.translation_type == ACPI_SPARSE_TRANSLATION) > sparse = 1; > ... > } > > > > > Bjorn > > > > > -- > Best regards > Tianyu Lan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/