Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753654Ab3GANwF (ORCPT ); Mon, 1 Jul 2013 09:52:05 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:56082 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752812Ab3GANwC (ORCPT ); Mon, 1 Jul 2013 09:52:02 -0400 From: "Rafael J. Wysocki" To: Mika Westerberg Cc: Bjorn Helgaas , "Kirill A. Shutemov" , Greg Kroah-Hartman , "Rafael J. Wysocki" , Jesse Barnes , Yinghai Lu , "Ronciak, John" , "Penner, Miles J" , Bruce Allan , Heikki Krogerus , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "x86@kernel.org" Subject: Re: [PATCH 1/6] PCI: acpiphp: do not check for SLOT_ENABLED in enable_device() Date: Mon, 01 Jul 2013 16:01:37 +0200 Message-ID: <1530651.ees8hXMYoR@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.10.0-rc5+; KDE/4.9.5; x86_64; ; ) In-Reply-To: <20130701093217.GG9294@intel.com> References: <1372177330-28013-1-git-send-email-mika.westerberg@linux.intel.com> <4600759.u0rXpSLd62@vostro.rjw.lan> <20130701093217.GG9294@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4325 Lines: 98 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 > > > wrote: > > > > Bjorn Helgaas wrote: > > > >> On Tue, Jun 25, 2013 at 10:22 AM, Mika Westerberg > > > >> wrote: > > > >> > From: "Kirill A. Shutemov" > > > >> > > > > >> > 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 > > > >> > Signed-off-by: Mika Westerberg > > > >> > --- > > > >> > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/