From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Jesse Barnes <jbarnes@virtuousgeek.org>,
Yinghai Lu <yinghai@kernel.org>,
"Ronciak, John" <john.ronciak@intel.com>,
"Penner, Miles J" <miles.j.penner@intel.com>,
Bruce Allan <bruce.w.allan@intel.com>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH 1/6] PCI: acpiphp: do not check for SLOT_ENABLED in enable_device()
Date: Fri, 28 Jun 2013 20:54:45 +0200 [thread overview]
Message-ID: <4600759.u0rXpSLd62@vostro.rjw.lan> (raw)
In-Reply-To: <CAErSpo7pLoiaOeCbL1yLjdSbW7n0E8NMfkLGYpj8N=bvYBRN5w@mail.gmail.com>
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@linux.intel.com> wrote:
> > Bjorn Helgaas wrote:
> >> On Tue, Jun 25, 2013 at 10:22 AM, Mika Westerberg
> >> <mika.westerberg@linux.intel.com> wrote:
> >> > From: "Kirill A. Shutemov" <kirill.shutemov@linux.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@linux.intel.com>
> >> > Signed-off-by: Mika Westerberg <mika.westerberg@linux.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.
Thanks,
Rafael
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
next prev parent reply other threads:[~2013-06-28 18:45 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-25 16:22 [PATCH 0/6] Thunderbolt workarounds take 2 Mika Westerberg
2013-06-25 16:22 ` [PATCH 1/6] PCI: acpiphp: do not check for SLOT_ENABLED in enable_device() Mika Westerberg
2013-06-26 23:28 ` Bjorn Helgaas
2013-06-27 13:25 ` Kirill A. Shutemov
2013-06-28 9:51 ` Kirill A. Shutemov
2013-06-28 17:00 ` Bjorn Helgaas
2013-06-28 18:54 ` Rafael J. Wysocki [this message]
2013-07-01 9:32 ` Mika Westerberg
2013-07-01 14:01 ` Rafael J. Wysocki
2013-07-01 18:36 ` Mika Westerberg
2013-07-02 1:29 ` Rafael J. Wysocki
2013-07-02 16:40 ` Bjorn Helgaas
2013-07-02 20:29 ` Rafael J. Wysocki
2013-07-02 20:31 ` Mika Westerberg
2013-07-02 20:49 ` Rafael J. Wysocki
2013-06-25 16:22 ` [PATCH 2/6] PCI: acpiphp: enable_device(): rescan even if no new devices on slot Mika Westerberg
2013-06-26 23:37 ` Bjorn Helgaas
2013-06-27 13:02 ` Mika Westerberg
2013-06-27 16:32 ` Mika Westerberg
2013-06-27 16:50 ` Bjorn Helgaas
2013-06-27 16:54 ` Bjorn Helgaas
2013-06-27 1:20 ` Yinghai Lu
2013-06-27 13:04 ` Mika Westerberg
2013-06-25 16:22 ` [PATCH 3/6] PCI: introduce pci_trim_stale_devices() Mika Westerberg
2013-06-25 17:47 ` Andy Shevchenko
2013-06-25 17:56 ` Kirill A. Shutemov
2013-06-28 19:59 ` Rafael J. Wysocki
2013-06-25 16:22 ` [PATCH 4/6] PCI: acpiphp: check for new devices on enabled host Mika Westerberg
2013-06-25 18:04 ` Andy Shevchenko
2013-06-26 9:39 ` Kirill A. Shutemov
2013-06-27 19:05 ` Yinghai Lu
2013-06-28 9:33 ` Kirill A. Shutemov
2013-06-28 16:22 ` Yinghai Lu
2013-06-28 20:04 ` Rafael J. Wysocki
2013-06-25 16:22 ` [PATCH 5/6] PCI: acpiphp: look _RMV method a bit deeper in the hierarhcy Mika Westerberg
2013-06-25 18:15 ` Andy Shevchenko
2013-06-25 18:31 ` Mika Westerberg
2013-06-25 18:31 ` Andy Shevchenko
2013-06-25 18:51 ` Mika Westerberg
2013-06-25 19:30 ` Andy Shevchenko
2013-07-02 10:44 ` Kirill A. Shutemov
2013-07-02 17:09 ` Bjorn Helgaas
2013-07-02 17:45 ` Kirill A. Shutemov
2013-07-02 20:48 ` Rafael J. Wysocki
2013-07-02 20:40 ` Rafael J. Wysocki
2013-06-25 16:22 ` [PATCH 6/6] x86/PCI: quirk Thunderbolt PCI-to-PCI bridges Mika Westerberg
2013-06-25 21:15 ` Jesse Barnes
2013-06-26 12:17 ` Mika Westerberg
2013-06-26 15:04 ` Greg Kroah-Hartman
2013-06-26 20:59 ` Bjorn Helgaas
2013-06-26 22:15 ` Alex Williamson
2013-06-27 13:09 ` Mika Westerberg
2013-06-26 22:18 ` Bjorn Helgaas
2013-06-26 22:26 ` Yinghai Lu
2013-06-26 22:31 ` Yinghai Lu
2013-06-26 22:44 ` Rafael J. Wysocki
2013-06-26 22:38 ` Yinghai Lu
2013-06-26 22:55 ` Bjorn Helgaas
2013-06-26 23:56 ` Yinghai Lu
2013-06-27 16:00 ` Bjorn Helgaas
2013-06-27 17:27 ` Yinghai Lu
2013-06-27 13:58 ` Mika Westerberg
2013-06-27 13:54 ` Mika Westerberg
2013-06-27 16:27 ` Mika Westerberg
2013-06-27 17:18 ` Yinghai Lu
2013-06-25 23:24 ` [PATCH 0/6] Thunderbolt workarounds take 2 Rafael J. Wysocki
2013-06-26 7:25 ` Mika Westerberg
2013-06-26 12:45 ` Rafael J. Wysocki
2013-06-26 19:48 ` Bjorn Helgaas
2013-06-26 20:01 ` Rafael J. Wysocki
2013-06-26 19:55 ` Bjorn Helgaas
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