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From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Martin Mokrejs <mmokrejs@fold.natur.cuni.cz>
Cc: Yinghai Lu <yinghai@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
	linux-pci@vger.kernel.org
Subject: Re: Dell Vostro 3550: pci_hotplug+acpiphp require 'pcie_aspm=force' on kernel command-line for hotplug to work
Date: Fri, 11 Jan 2013 22:11:26 +0100
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On Thursday, January 10, 2013 03:04:26 AM Martin Mokrejs wrote:
> Hi Yinghai,
>   thank you for you answer, it is way too late here but a quick answer ...
> 
> Yinghai Lu wrote:
> > On Wed, Jan 9, 2013 at 3:10 PM, Martin Mokrejs
> > <mmokrejs@fold.natur.cuni.cz> wrote:
> >> - pci0000:00: Requesting ACPI _OSC control (0x1d)
> >> - pci0000:00: ACPI _OSC control (0x19) granted
> >> + pci0000:00: Unable to request _OSC control (_OSC support mask: 0x19)
> > 
> > according to _OSC related game in acpi_pci_root_add()
> > it will query_osc_support with flags |=
> >                                 OSC_EXT_PCI_CONFIG_SUPPORT \
> >                                 | OSC_ACTIVE_STATE_PWR_SUPPORT \
> >                                 | OSC_CLOCK_PWR_CAPABILITY_SUPPORT \
> >                                 | OSC_MSI_SUPPORT
> > and the firmware should not return ACPI FAILURE, and if it return
> > failure, flags will get reset.
> > 
> > then if and only if flags keep there five bits, kernel will try to set control
> > to _OSC for
> >                         OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL
> >                         | OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
> >                         | OSC_PCI_EXPRESS_PME_CONTROL;
> > and may be AER.
> > 
> > that will let pciehp own the device <pciehp will claim that later...>
> > 
> > in acpiphp there is module that will check if port is owned by pciehp,
> > and it will bail out early.
> > in device_is_managed_by_native_pciehp...
> > 
> > pcie_aspm=off will stop all _osc setting, like pciehp, pme and aer.
> > 
> > the checking in acpiphp is introduced by:
> > commit 0d52f54e2ef64c189dedc332e680b2eb4a34590a
> > Author: Rafael J. Wysocki <rjw@sisk.pl>
> > Date:   Sat Oct 22 00:43:38 2011 +0200
> > 
> >     PCI / ACPI: Make acpiphp ignore root bridges using PCIe native hotplug
> > 
> > so it is a regression.
> 
> It is true that since the time around 3.3.x when I reported the problem I had in
> grub.conf kept pcie_aspm=force.

Have you tried pcie_ports=compat?

This is the command line option to use in such cases, in theory.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.