From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <5579BFD9.9040904@redhat.com> Date: Thu, 11 Jun 2015 13:05:29 -0400 From: Jarod Wilson MIME-Version: 1.0 To: "Rafael J. Wysocki" , Bjorn Helgaas CC: linux-kernel@vger.kernel.org, Len Brown , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [Update][PATCH] PCIe / hotplug: Drop pointless ACPI-based "slot detection" check References: <1431632038-39917-1-git-send-email-jarod@redhat.com> <1573807.HQlNd2BFYP@vostro.rjw.lan> <20150521161146.GE32152@google.com> <3372859.5Hat5UqSL7@vostro.rjw.lan> In-Reply-To: <3372859.5Hat5UqSL7@vostro.rjw.lan> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: On 5/21/2015 9:21 PM, Rafael J. Wysocki wrote: > On Thursday, May 21, 2015 11:11:46 AM Bjorn Helgaas wrote: >> On Tue, May 19, 2015 at 03:27:58PM +0200, Rafael J. Wysocki wrote: >>> From: Rafael J. Wysocki >>> >>> Jarod Wilson reports that the expresscard hotplug setup doesn't work >>> on HP ZBook G2. The problem turns out to be the ACPI-based "slot >>> detection" code called from pciehp_probe() which tries to use some >>> questionable heuristics based on what ACPI objects are present for >>> the PCIe port device at hand to figure out whether or not to register >>> a hotplug slot for that port. >>> >>> That code is used if there is at least one PCIe port having an ACPI >>> device configuration object related to hotplug (such as _EJ0 or _RMV) >>> and the Thunderbolt port on the affected machine has _RMV. Of course, >>> Thunderbolt and PCIe native hotplug need not be mutually exclusive >>> (as they aren't on the machine in question), so that rule is simply >>> incorrect. >>> >>> Moreover, the ACPI-based "slot detection" check does not add any >>> value if pciehp_probe() is called at all and the service type of the >>> device object it has been called for is PCIE_PORT_SERVICE_HP, because >>> PCIe hotplug services are only registered if the _OSC handshake in >>> acpi_pci_root_add() allows the kernel to control the PCIe native >>> hotplug feature. No more checks need to be carried out to decide >>> whether or not to register a native PCIe hotlug slot in that case. >>> >>> For the above reasons, make pciehp_probe() check if it has been >>> called for the right service type and drop the pointless ACPI-based >>> "slot detection" check from it. Also remove the entire code whose >>> only user is that check (the entire pciehp_acpi.c file goes away >>> as a result) and drop function headers related to it from the >>> internal PCIeHP header file. >>> >>> Link: http://marc.info/?t=143163219300002&r=1&w=2 >>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=98581 >>> Reported-by: Jarod Wilson >>> Signed-off-by: Rafael J. Wysocki >> >> This is awesome! Applied to pci/hotplug for v4.2, with Jarod's >> reviewed/tested-by. > > Thanks! Looks like I didn't test enough. I can't explain WHY, but with this applied, now thunderbolt hot unplug of a network adapter goes haywire, where prior to the patch, it worked just fine. Still looking into it... -- Jarod Wilson jarod@redhat.com