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Date: Mon, 01 Jul 2013 16:01:37 +0200 From: "Rafael J. Wysocki" <rjw@...k.pl> To: Mika Westerberg <mika.westerberg@...ux.intel.com> Cc: Bjorn Helgaas <bhelgaas@...gle.com>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, Jesse Barnes <jbarnes@...tuousgeek.org>, Yinghai Lu <yinghai@...nel.org>, "Ronciak, John" <john.ronciak@...el.com>, "Penner, Miles J" <miles.j.penner@...el.com>, Bruce Allan <bruce.w.allan@...el.com>, Heikki Krogerus <heikki.krogerus@...ux.intel.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>, "x86@...nel.org" <x86@...nel.org> Subject: Re: [PATCH 1/6] PCI: acpiphp: do not check for SLOT_ENABLED in enable_device() On Monday, July 01, 2013 12:32:17 PM Mika Westerberg wrote: > On Fri, Jun 28, 2013 at 08:54:45PM +0200, Rafael J. Wysocki wrote: > > On Friday, June 28, 2013 11:00:31 AM Bjorn Helgaas wrote: > > > On Fri, Jun 28, 2013 at 3:51 AM, Kirill A. Shutemov > > > <kirill.shutemov@...ux.intel.com> wrote: > > > > Bjorn Helgaas wrote: > > > >> On Tue, Jun 25, 2013 at 10:22 AM, Mika Westerberg > > > >> <mika.westerberg@...ux.intel.com> wrote: > > > >> > From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> > > > >> > > > > >> > With Thunderbolt you can chain devices: connect a new devices to plugged > > > >> > one. In this case the slot is already enabled, but we still want to look > > > >> > for new devices behind it. > > > >> > > > > >> > We're going to reuse enable_device() for rescan for new devices on the > > > >> > enabled slot. Let's push the check up by stack. > > > >> > > > > >> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com> > > > >> > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com> > > > >> > --- > > > >> > drivers/pci/hotplug/acpiphp_glue.c | 5 ++--- > > > >> > 1 file changed, 2 insertions(+), 3 deletions(-) > > > >> > > > > >> > diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c > > > >> > index 59df857..b983e29 100644 > > > >> > --- a/drivers/pci/hotplug/acpiphp_glue.c > > > >> > +++ b/drivers/pci/hotplug/acpiphp_glue.c > > > >> > @@ -688,9 +688,6 @@ static int __ref enable_device(struct acpiphp_slot *slot) > > > >> > int num, max, pass; > > > >> > LIST_HEAD(add_list); > > > >> > > > > >> > - if (slot->flags & SLOT_ENABLED) > > > >> > - goto err_exit; > > > >> > - > > > >> > list_for_each_entry(func, &slot->funcs, sibling) > > > >> > acpiphp_bus_add(func); > > > >> > > > > >> > @@ -1242,6 +1239,8 @@ int acpiphp_enable_slot(struct acpiphp_slot *slot) > > > >> > goto err_exit; > > > >> > > > > >> > if (get_slot_status(slot) == ACPI_STA_ALL) { > > > >> > + if (slot->flags & SLOT_ENABLED) > > > >> > + goto err_exit; > > > >> > > > >> Why do we check for SLOT_ENABLED at all? I think we're handling a Bus > > > >> Check notification, which means "re-enumerate on the device tree > > > >> starting from the notification point." It doesn't say anything about > > > >> skipping the re-enumeration if we find a device that's already > > > >> enabled. > > > >> > > > >> It seems like we ought to just re-enumerate all the way down in case a > > > >> device was added farther down in the tree (which is what it sounds > > > >> like Thunderbolt is doing). > > > > > > > > Currently (with patchset applied), we have two users of > > > > acpiphp_enable_slot(): > > > > > > > > - /sys/bus/pci/slots/*/power > > > > - ACPI_NOTIFY_BUS_CHECK in _handle_hotplug_event_func(). > > > > > > > > Both are not related to Thunderbolt. > > > > > > > > Although, I think remove the check is good idea, I prefer to keep it > > > > separate from Thunderbolt enabling patchset, since it will change sysfs > > > > ABI a bit and can potentially affect othe ACPI PCI hotplug > > > > implementations. > > > > > > I'll think about this some more, but if we can make a change that > > > simplifies things and makes them more spec-compliant, and also happens > > > to make Thunderbolt work, that sounds better than fixing Thunderbolt > > > while leaving the wart there. > > > > > > If we only fix Thunderbolt, it just feels like we're adding to an > > > ever-growing "deferred maintenance" list. > > > > I agree. > > > > That change may be done in a separate patch, but it should be included in the > > series. > > Given the fact that SLOT_ENABLED is only checked in acpiphp_enable_slot() > (after this patch) and that /sys/bus/pci/slots/*/power uses SLOT_POWEREDON > anyway, should we remove the whole flag? Sure, if it is not necessary any more, we should remove it. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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