From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f174.google.com ([209.85.217.174]:41510 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932356Ab2GKTmh (ORCPT ); Wed, 11 Jul 2012 15:42:37 -0400 Received: by lbbgm6 with SMTP id gm6so2900837lbb.19 for ; Wed, 11 Jul 2012 12:42:35 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20120711171458.GA14610@redhat.com> References: <1340437325-29282-1-git-send-email-yinghai@kernel.org> <1340437325-29282-5-git-send-email-yinghai@kernel.org> <20120711171458.GA14610@redhat.com> From: Bjorn Helgaas Date: Wed, 11 Jul 2012 13:42:15 -0600 Message-ID: Subject: Re: [PATCH 4/5] PCI, acpiphp: add is_hotplug_bridge detection To: Jason Baron Cc: Yinghai Lu , linux-pci@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-pci-owner@vger.kernel.org List-ID: On Wed, Jul 11, 2012 at 11:14 AM, Jason Baron wrote: > On Wed, Jul 11, 2012 at 09:50:19AM -0600, Bjorn Helgaas wrote: >> On Sat, Jun 23, 2012 at 1:42 AM, Yinghai Lu wrote: >> > When system support hotplug bridge with children hotplug slots, we need to make sure >> > that parent bridge get preallocated resource so later when device is plugged into >> > children slot, those children devices will get resource allocated. >> > >> > We do not meet this problem, because for pcie hotplug card, when acpiphp is used, >> > pci_scan_bridge will set that for us when detect hotplug bit in slot cap. >> > >> > Reported-and-tested-by: Jason Baron >> > Signed-off-by: Yinghai Lu >> > Acked-by: Jason Baron >> > --- >> > drivers/pci/hotplug/acpiphp_glue.c | 27 ++++++++++++++++++++++++++- >> > 1 files changed, 26 insertions(+), 1 deletions(-) >> > >> > diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c >> > index ad6fd66..0f2b72d 100644 >> > --- a/drivers/pci/hotplug/acpiphp_glue.c >> > +++ b/drivers/pci/hotplug/acpiphp_glue.c >> > @@ -783,6 +783,29 @@ static void acpiphp_set_acpi_region(struct acpiphp_slot *slot) >> > } >> > } >> > >> > +static void check_hotplug_bridge(struct acpiphp_slot *slot, struct pci_dev *dev) >> > +{ >> > + struct acpiphp_func *func; >> > + >> > + if (!dev->subordinate) >> > + return; >> > + >> > + /* quirk, or pcie could set it already */ >> > + if (dev->is_hotplug_bridge) >> > + return; >> > + >> > + if (PCI_SLOT(dev->devfn) != slot->device) >> > + return; >> > + >> > + list_for_each_entry(func, &slot->funcs, sibling) { >> > + if (PCI_FUNC(dev->devfn) == func->function) { >> > + /* check if this bridge has ejectable slots */ >> > + if ((detect_ejectable_slots(func->handle) > 0)) >> > + dev->is_hotplug_bridge = 1; >> > + break; >> > + } >> > + } >> > +} >> > /** >> > * enable_device - enable, configure a slot >> > * @slot: slot to be enabled >> > @@ -817,8 +840,10 @@ static int __ref enable_device(struct acpiphp_slot *slot) >> > if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE || >> > dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) { >> > max = pci_scan_bridge(bus, dev, max, pass); >> > - if (pass && dev->subordinate) >> > + if (pass && dev->subordinate) { >> > + check_hotplug_bridge(slot, dev); >> >> I don't like this patch because it increases the differences between >> the hotplug drivers, rather than decreasing them. >> >> For PCI Express devices, we set dev->is_hotplug_bridge in the >> pci_setup_device() path (in set_pcie_hotplug_bridge()). I think it >> would make sense to try to expand that path to also handle SHPC and >> ACPI hotplug as well. ACPI is harder because it's not PCI-specified, >> so we'd need some sort of pcibios or other optional hook. >> >> I don't have a clear picture of how this works -- if I understand >> correctly, the situation is that we have a bridge managed by acpiphp. >> That part makes sense because the bridge is on the motherboard and can >> have a DSDT device. Now we plug something into the slot below the >> bridge. I *think* this patch handles the case where this new >> hot-added thing is also a bridge managed by acpiphp. But where does >> the ACPI device for this hot-added bridge come from? It's an >> arbitrary device the BIOS knows nothing about, so it can't be in the >> DSDT. >> > > So this came up while I was developing pci bridge hotplug for qemu. > Currently, there is a top level host bus (with ACPI device definitions), where > devices can be hot-plugged. What I've done is added a second level > of hotplug pci busses (again with ACPI device definitions). Thus, we can > now hotplug a bridge into the top-level bus and then devices behind it. > Effectively increasing the hot-plug space from n -> n^2. > > Before the above pci patch, the devices behind the bridge would not > configure their PCI BARs properly, since there were no i/o, mem resources > assigned to the bridge. However, with the above patch in place things > work as expected. > > Using the same code base I was able to do acpi hotplug on Windows 7, > which correctly configured the both the bridge window and devices behind > it on hot-plug. So currently, the above usage pattern works on Windows > 7, but not on Linux. Thanks, Jason. Do you have "lspci -v" output and the DSDT AML handy? I'd like to look in more detail at what we're missing.