From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lan Tianyu Date: Wed, 30 Oct 2013 08:34:04 +0000 Subject: Re: [Resend PATCH 5/5] IA64/PCI/ACPI: Rework PCI root bridge ACPI resource conversion Message-Id: <5270C47C.5040206@intel.com> List-Id: References: <1381493941-4650-1-git-send-email-tianyu.lan@intel.com> <1381493941-4650-6-git-send-email-tianyu.lan@intel.com> <20131016235541.GD17866@google.com> <525F7F0F.5010306@intel.com> <52612D1C.4070701@intel.com> <20131023223904.GA18454@google.com> <526BF37E.8040801@intel.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: Bjorn Helgaas 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" 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? 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? > > Bjorn > -- Best regards Tianyu Lan