[PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
pci_acpi_scan_root before setting the osc flags for the device handle.
pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
to determine if a given slot has pcie hotplug capabilties, whcih checks the
devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
slots are hotplug capable and configures them all to use acpi instead.

Fix is pretty simple, just defer the scan until after the osc flags have been
set on the device.  Tested by myself and it seems to work well.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Len Brown <lenb@kernel.org>
CC: "Rafael J. Wysocki" <rjw@sisk.pl>
CC: linux-acpi@vger.kernel.org
---
 drivers/acpi/pci_root.c | 41 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 5917839..a2c2661 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 	acpi_pci_osc_support(root, flags);
 
-	/*
-	 * TBD: Need PCI interface for enumeration/configuration of roots.
-	 */
-
-	/*
-	 * Scan the Root Bridge
-	 * --------------------
-	 * Must do this prior to any attempt to bind the root device, as the
-	 * PCI namespace does not get created until this call is made (and
-	 * thus the root bridge's pci_dev does not exist).
-	 */
-	root->bus = pci_acpi_scan_root(root);
-	if (!root->bus) {
-		dev_err(&device->dev,
-			"Bus %04x:%02x not present in PCI namespace\n",
-			root->segment, (unsigned int)root->secondary.start);
-		result = -ENODEV;
-		goto end;
-	}
-
-	/* Indicate support for various _OSC capabilities. */
 	if (pci_ext_cfg_avail())
 		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
 	if (pcie_aspm_support_enabled()) {
@@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device,
 			 "(_OSC support mask: 0x%02x)\n", flags);
 	}
 
+	/*
+	 * TBD: Need PCI interface for enumeration/configuration of roots.
+	 */
+
+	/*
+	 * Scan the Root Bridge
+	 * --------------------
+	 * Must do this prior to any attempt to bind the root device, as the
+	 * PCI namespace does not get created until this call is made (and
+	 * thus the root bridge's pci_dev does not exist).
+	 */
+	root->bus = pci_acpi_scan_root(root);
+	if (!root->bus) {
+		dev_err(&device->dev,
+			"Bus %04x:%02x not present in PCI namespace\n",
+			root->segment, (unsigned int)root->secondary.start);
+		result = -ENODEV;
+		goto end;
+	}
+
 	pci_acpi_add_bus_pm_notifier(device, root->bus);
 	if (device->wakeup.flags.run_wake)
 		device_set_run_wake(root->bus->bridge, true);
-- 
1.8.1.4

Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Rafael J. Wysocki]

[CCs added]

Please always send PCI-related material to linux-pci in the first place.

The change that broke things for you was actually intentional:

commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Mon Apr 1 15:47:39 2013 -0600

    Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
    
    This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.

so I think we'll need to clean up the ASMP initialization after all.

On Friday, August 23, 2013 01:19:39 PM Neil Horman wrote:
> Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> pci_acpi_scan_root before setting the osc flags for the device handle.
> pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> to determine if a given slot has pcie hotplug capabilties, whcih checks the
> devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> slots are hotplug capable and configures them all to use acpi instead.
> 
> Fix is pretty simple, just defer the scan until after the osc flags have been
> set on the device.  Tested by myself and it seems to work well.
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> CC: Len Brown <lenb@kernel.org>
> CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> CC: linux-acpi@vger.kernel.org
> ---
>  drivers/acpi/pci_root.c | 41 ++++++++++++++++++++---------------------
>  1 file changed, 20 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 5917839..a2c2661 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
>  	acpi_pci_osc_support(root, flags);
>  
> -	/*
> -	 * TBD: Need PCI interface for enumeration/configuration of roots.
> -	 */
> -
> -	/*
> -	 * Scan the Root Bridge
> -	 * --------------------
> -	 * Must do this prior to any attempt to bind the root device, as the
> -	 * PCI namespace does not get created until this call is made (and
> -	 * thus the root bridge's pci_dev does not exist).
> -	 */
> -	root->bus = pci_acpi_scan_root(root);
> -	if (!root->bus) {
> -		dev_err(&device->dev,
> -			"Bus %04x:%02x not present in PCI namespace\n",
> -			root->segment, (unsigned int)root->secondary.start);
> -		result = -ENODEV;
> -		goto end;
> -	}
> -
> -	/* Indicate support for various _OSC capabilities. */
>  	if (pci_ext_cfg_avail())
>  		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>  	if (pcie_aspm_support_enabled()) {
> @@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  			 "(_OSC support mask: 0x%02x)\n", flags);
>  	}
>  
> +	/*
> +	 * TBD: Need PCI interface for enumeration/configuration of roots.
> +	 */
> +
> +	/*
> +	 * Scan the Root Bridge
> +	 * --------------------
> +	 * Must do this prior to any attempt to bind the root device, as the
> +	 * PCI namespace does not get created until this call is made (and
> +	 * thus the root bridge's pci_dev does not exist).
> +	 */
> +	root->bus = pci_acpi_scan_root(root);
> +	if (!root->bus) {
> +		dev_err(&device->dev,
> +			"Bus %04x:%02x not present in PCI namespace\n",
> +			root->segment, (unsigned int)root->secondary.start);
> +		result = -ENODEV;
> +		goto end;
> +	}
> +
>  	pci_acpi_add_bus_pm_notifier(device, root->bus);
>  	if (device->wakeup.flags.run_wake)
>  		device_set_run_wake(root->bus->bridge, true);
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

On Fri, Aug 23, 2013 at 09:38:18PM +0200, Rafael J. Wysocki wrote:
> [CCs added]
> 
> Please always send PCI-related material to linux-pci in the first place.
> 
Sorry, I ran get_maintainers and it seemed to think linux-acpi was sufficient.

> The change that broke things for you was actually intentional:
> 
> commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> Author: Bjorn Helgaas <bhelgaas@google.com>
> Date:   Mon Apr 1 15:47:39 2013 -0600
> 
>     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
>     
>     This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.
> 
> so I think we'll need to clean up the ASMP initialization after all.
> 
Crud.  Reading over the revert commit, it seems like the problem boils down to
the odering of checking aspm_disabled.  It seems to me that the simple fix is to
track the desire for acpi to disable aspm separately from the users desire to
disable aspm (aspm_disabled).  Then we just turn the points where we check the
aspm_disabled into the appropriate or of two variables, except for
pcie_asmp_sanity_check, which remains sensitive to just the user disable option.

Or is there more to this?

Neil

> On Friday, August 23, 2013 01:19:39 PM Neil Horman wrote:
> > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> > pci_acpi_scan_root before setting the osc flags for the device handle.
> > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> > to determine if a given slot has pcie hotplug capabilties, whcih checks the
> > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> > slots are hotplug capable and configures them all to use acpi instead.
> > 
> > Fix is pretty simple, just defer the scan until after the osc flags have been
> > set on the device.  Tested by myself and it seems to work well.
> > 
> > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > CC: Len Brown <lenb@kernel.org>
> > CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> > CC: linux-acpi@vger.kernel.org
> > ---
> >  drivers/acpi/pci_root.c | 41 ++++++++++++++++++++---------------------
> >  1 file changed, 20 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > index 5917839..a2c2661 100644
> > --- a/drivers/acpi/pci_root.c
> > +++ b/drivers/acpi/pci_root.c
> > @@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >  	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
> >  	acpi_pci_osc_support(root, flags);
> >  
> > -	/*
> > -	 * TBD: Need PCI interface for enumeration/configuration of roots.
> > -	 */
> > -
> > -	/*
> > -	 * Scan the Root Bridge
> > -	 * --------------------
> > -	 * Must do this prior to any attempt to bind the root device, as the
> > -	 * PCI namespace does not get created until this call is made (and
> > -	 * thus the root bridge's pci_dev does not exist).
> > -	 */
> > -	root->bus = pci_acpi_scan_root(root);
> > -	if (!root->bus) {
> > -		dev_err(&device->dev,
> > -			"Bus %04x:%02x not present in PCI namespace\n",
> > -			root->segment, (unsigned int)root->secondary.start);
> > -		result = -ENODEV;
> > -		goto end;
> > -	}
> > -
> > -	/* Indicate support for various _OSC capabilities. */
> >  	if (pci_ext_cfg_avail())
> >  		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
> >  	if (pcie_aspm_support_enabled()) {
> > @@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >  			 "(_OSC support mask: 0x%02x)\n", flags);
> >  	}
> >  
> > +	/*
> > +	 * TBD: Need PCI interface for enumeration/configuration of roots.
> > +	 */
> > +
> > +	/*
> > +	 * Scan the Root Bridge
> > +	 * --------------------
> > +	 * Must do this prior to any attempt to bind the root device, as the
> > +	 * PCI namespace does not get created until this call is made (and
> > +	 * thus the root bridge's pci_dev does not exist).
> > +	 */
> > +	root->bus = pci_acpi_scan_root(root);
> > +	if (!root->bus) {
> > +		dev_err(&device->dev,
> > +			"Bus %04x:%02x not present in PCI namespace\n",
> > +			root->segment, (unsigned int)root->secondary.start);
> > +		result = -ENODEV;
> > +		goto end;
> > +	}
> > +
> >  	pci_acpi_add_bus_pm_notifier(device, root->bus);
> >  	if (device->wakeup.flags.run_wake)
> >  		device_set_run_wake(root->bus->bridge, true);
> > 
> -- 
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
> 

Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Bjorn Helgaas]

On Fri, Aug 23, 2013 at 2:53 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> On Friday, August 23, 2013 04:05:11 PM Neil Horman wrote:
>> On Fri, Aug 23, 2013 at 09:38:18PM +0200, Rafael J. Wysocki wrote:
>> > [CCs added]
>> >
>> > Please always send PCI-related material to linux-pci in the first place.
>> >
>> Sorry, I ran get_maintainers and it seemed to think linux-acpi was sufficient.
>>
>> > The change that broke things for you was actually intentional:
>> >
>> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
>> > Author: Bjorn Helgaas <bhelgaas@google.com>
>> > Date:   Mon Apr 1 15:47:39 2013 -0600
>> >
>> >     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
>> >
>> >     This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.
>> >
>> > so I think we'll need to clean up the ASMP initialization after all.
>> >
>> Crud.  Reading over the revert commit, it seems like the problem boils down to
>> the odering of checking aspm_disabled.  It seems to me that the simple fix is to
>> track the desire for acpi to disable aspm separately from the users desire to
>> disable aspm (aspm_disabled).  Then we just turn the points where we check the
>> aspm_disabled into the appropriate or of two variables, except for
>> pcie_asmp_sanity_check, which remains sensitive to just the user disable option.
>>
>> Or is there more to this?
>
> No, I think you're right.
>
> Bjorn, what do you think?

My opinion is that the _OSC/ASPM state management is ridiculously
complicated already, and this would make it slightly more complicated.
 That's why my preference would be to attempt a more radical cleanup
and simplification instead of adding another wart.

But if you want to merge a patch along the lines of what Neil
proposes, I won't object.

Bjorn

>> > On Friday, August 23, 2013 01:19:39 PM Neil Horman wrote:
>> > > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
>> > > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
>> > > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
>> > > pci_acpi_scan_root before setting the osc flags for the device handle.
>> > > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
>> > > to determine if a given slot has pcie hotplug capabilties, whcih checks the
>> > > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
>> > > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
>> > > slots are hotplug capable and configures them all to use acpi instead.
>> > >
>> > > Fix is pretty simple, just defer the scan until after the osc flags have been
>> > > set on the device.  Tested by myself and it seems to work well.
>> > >
>> > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
>> > > CC: Len Brown <lenb@kernel.org>
>> > > CC: "Rafael J. Wysocki" <rjw@sisk.pl>
>> > > CC: linux-acpi@vger.kernel.org
>> > > ---
>> > >  drivers/acpi/pci_root.c | 41 ++++++++++++++++++++---------------------
>> > >  1 file changed, 20 insertions(+), 21 deletions(-)
>> > >
>> > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> > > index 5917839..a2c2661 100644
>> > > --- a/drivers/acpi/pci_root.c
>> > > +++ b/drivers/acpi/pci_root.c
>> > > @@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
>> > >   flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
>> > >   acpi_pci_osc_support(root, flags);
>> > >
>> > > - /*
>> > > -  * TBD: Need PCI interface for enumeration/configuration of roots.
>> > > -  */
>> > > -
>> > > - /*
>> > > -  * Scan the Root Bridge
>> > > -  * --------------------
>> > > -  * Must do this prior to any attempt to bind the root device, as the
>> > > -  * PCI namespace does not get created until this call is made (and
>> > > -  * thus the root bridge's pci_dev does not exist).
>> > > -  */
>> > > - root->bus = pci_acpi_scan_root(root);
>> > > - if (!root->bus) {
>> > > -         dev_err(&device->dev,
>> > > -                 "Bus %04x:%02x not present in PCI namespace\n",
>> > > -                 root->segment, (unsigned int)root->secondary.start);
>> > > -         result = -ENODEV;
>> > > -         goto end;
>> > > - }
>> > > -
>> > > - /* Indicate support for various _OSC capabilities. */
>> > >   if (pci_ext_cfg_avail())
>> > >           flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>> > >   if (pcie_aspm_support_enabled()) {
>> > > @@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device,
>> > >                    "(_OSC support mask: 0x%02x)\n", flags);
>> > >   }
>> > >
>> > > + /*
>> > > +  * TBD: Need PCI interface for enumeration/configuration of roots.
>> > > +  */
>> > > +
>> > > + /*
>> > > +  * Scan the Root Bridge
>> > > +  * --------------------
>> > > +  * Must do this prior to any attempt to bind the root device, as the
>> > > +  * PCI namespace does not get created until this call is made (and
>> > > +  * thus the root bridge's pci_dev does not exist).
>> > > +  */
>> > > + root->bus = pci_acpi_scan_root(root);
>> > > + if (!root->bus) {
>> > > +         dev_err(&device->dev,
>> > > +                 "Bus %04x:%02x not present in PCI namespace\n",
>> > > +                 root->segment, (unsigned int)root->secondary.start);
>> > > +         result = -ENODEV;
>> > > +         goto end;
>> > > + }
>> > > +
>> > >   pci_acpi_add_bus_pm_notifier(device, root->bus);
>> > >   if (device->wakeup.flags.run_wake)
>> > >           device_set_run_wake(root->bus->bridge, true);
>> > >
>>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Rafael J. Wysocki]

On Friday, August 23, 2013 04:05:11 PM Neil Horman wrote:
> On Fri, Aug 23, 2013 at 09:38:18PM +0200, Rafael J. Wysocki wrote:
> > [CCs added]
> > 
> > Please always send PCI-related material to linux-pci in the first place.
> > 
> Sorry, I ran get_maintainers and it seemed to think linux-acpi was sufficient.
> 
> > The change that broke things for you was actually intentional:
> > 
> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> > Author: Bjorn Helgaas <bhelgaas@google.com>
> > Date:   Mon Apr 1 15:47:39 2013 -0600
> > 
> >     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
> >     
> >     This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.
> > 
> > so I think we'll need to clean up the ASMP initialization after all.
> > 
> Crud.  Reading over the revert commit, it seems like the problem boils down to
> the odering of checking aspm_disabled.  It seems to me that the simple fix is to
> track the desire for acpi to disable aspm separately from the users desire to
> disable aspm (aspm_disabled).  Then we just turn the points where we check the
> aspm_disabled into the appropriate or of two variables, except for
> pcie_asmp_sanity_check, which remains sensitive to just the user disable option.
> 
> Or is there more to this?

No, I think you're right.

Bjorn, what do you think?

Rafael


> > On Friday, August 23, 2013 01:19:39 PM Neil Horman wrote:
> > > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> > > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> > > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> > > pci_acpi_scan_root before setting the osc flags for the device handle.
> > > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> > > to determine if a given slot has pcie hotplug capabilties, whcih checks the
> > > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> > > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> > > slots are hotplug capable and configures them all to use acpi instead.
> > > 
> > > Fix is pretty simple, just defer the scan until after the osc flags have been
> > > set on the device.  Tested by myself and it seems to work well.
> > > 
> > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > > CC: Len Brown <lenb@kernel.org>
> > > CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> > > CC: linux-acpi@vger.kernel.org
> > > ---
> > >  drivers/acpi/pci_root.c | 41 ++++++++++++++++++++---------------------
> > >  1 file changed, 20 insertions(+), 21 deletions(-)
> > > 
> > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > > index 5917839..a2c2661 100644
> > > --- a/drivers/acpi/pci_root.c
> > > +++ b/drivers/acpi/pci_root.c
> > > @@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
> > >  	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
> > >  	acpi_pci_osc_support(root, flags);
> > >  
> > > -	/*
> > > -	 * TBD: Need PCI interface for enumeration/configuration of roots.
> > > -	 */
> > > -
> > > -	/*
> > > -	 * Scan the Root Bridge
> > > -	 * --------------------
> > > -	 * Must do this prior to any attempt to bind the root device, as the
> > > -	 * PCI namespace does not get created until this call is made (and
> > > -	 * thus the root bridge's pci_dev does not exist).
> > > -	 */
> > > -	root->bus = pci_acpi_scan_root(root);
> > > -	if (!root->bus) {
> > > -		dev_err(&device->dev,
> > > -			"Bus %04x:%02x not present in PCI namespace\n",
> > > -			root->segment, (unsigned int)root->secondary.start);
> > > -		result = -ENODEV;
> > > -		goto end;
> > > -	}
> > > -
> > > -	/* Indicate support for various _OSC capabilities. */
> > >  	if (pci_ext_cfg_avail())
> > >  		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
> > >  	if (pcie_aspm_support_enabled()) {
> > > @@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device,
> > >  			 "(_OSC support mask: 0x%02x)\n", flags);
> > >  	}
> > >  
> > > +	/*
> > > +	 * TBD: Need PCI interface for enumeration/configuration of roots.
> > > +	 */
> > > +
> > > +	/*
> > > +	 * Scan the Root Bridge
> > > +	 * --------------------
> > > +	 * Must do this prior to any attempt to bind the root device, as the
> > > +	 * PCI namespace does not get created until this call is made (and
> > > +	 * thus the root bridge's pci_dev does not exist).
> > > +	 */
> > > +	root->bus = pci_acpi_scan_root(root);
> > > +	if (!root->bus) {
> > > +		dev_err(&device->dev,
> > > +			"Bus %04x:%02x not present in PCI namespace\n",
> > > +			root->segment, (unsigned int)root->secondary.start);
> > > +		result = -ENODEV;
> > > +		goto end;
> > > +	}
> > > +
> > >  	pci_acpi_add_bus_pm_notifier(device, root->bus);
> > >  	if (device->wakeup.flags.run_wake)
> > >  		device_set_run_wake(root->bus->bridge, true);
> > > 
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Rafael J. Wysocki]

On Friday, August 23, 2013 02:46:23 PM Bjorn Helgaas wrote:
> On Fri, Aug 23, 2013 at 2:53 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > On Friday, August 23, 2013 04:05:11 PM Neil Horman wrote:
> >> On Fri, Aug 23, 2013 at 09:38:18PM +0200, Rafael J. Wysocki wrote:
> >> > [CCs added]
> >> >
> >> > Please always send PCI-related material to linux-pci in the first place.
> >> >
> >> Sorry, I ran get_maintainers and it seemed to think linux-acpi was sufficient.
> >>
> >> > The change that broke things for you was actually intentional:
> >> >
> >> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> >> > Author: Bjorn Helgaas <bhelgaas@google.com>
> >> > Date:   Mon Apr 1 15:47:39 2013 -0600
> >> >
> >> >     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
> >> >
> >> >     This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.
> >> >
> >> > so I think we'll need to clean up the ASMP initialization after all.
> >> >
> >> Crud.  Reading over the revert commit, it seems like the problem boils down to
> >> the odering of checking aspm_disabled.  It seems to me that the simple fix is to
> >> track the desire for acpi to disable aspm separately from the users desire to
> >> disable aspm (aspm_disabled).  Then we just turn the points where we check the
> >> aspm_disabled into the appropriate or of two variables, except for
> >> pcie_asmp_sanity_check, which remains sensitive to just the user disable option.
> >>
> >> Or is there more to this?
> >
> > No, I think you're right.
> >
> > Bjorn, what do you think?
> 
> My opinion is that the _OSC/ASPM state management is ridiculously
> complicated already, and this would make it slightly more complicated.
>  That's why my preference would be to attempt a more radical cleanup
> and simplification instead of adding another wart.

Well, do you have anything specific in mind?

> But if you want to merge a patch along the lines of what Neil
> proposes, I won't object.

I'm not sure what to do really, so I'm asking. :-)

Rafael


> >> > On Friday, August 23, 2013 01:19:39 PM Neil Horman wrote:
> >> > > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> >> > > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> >> > > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> >> > > pci_acpi_scan_root before setting the osc flags for the device handle.
> >> > > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> >> > > to determine if a given slot has pcie hotplug capabilties, whcih checks the
> >> > > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> >> > > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> >> > > slots are hotplug capable and configures them all to use acpi instead.
> >> > >
> >> > > Fix is pretty simple, just defer the scan until after the osc flags have been
> >> > > set on the device.  Tested by myself and it seems to work well.
> >> > >
> >> > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> >> > > CC: Len Brown <lenb@kernel.org>
> >> > > CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> >> > > CC: linux-acpi@vger.kernel.org
> >> > > ---
> >> > >  drivers/acpi/pci_root.c | 41 ++++++++++++++++++++---------------------
> >> > >  1 file changed, 20 insertions(+), 21 deletions(-)
> >> > >
> >> > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> >> > > index 5917839..a2c2661 100644
> >> > > --- a/drivers/acpi/pci_root.c
> >> > > +++ b/drivers/acpi/pci_root.c
> >> > > @@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >> > >   flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
> >> > >   acpi_pci_osc_support(root, flags);
> >> > >
> >> > > - /*
> >> > > -  * TBD: Need PCI interface for enumeration/configuration of roots.
> >> > > -  */
> >> > > -
> >> > > - /*
> >> > > -  * Scan the Root Bridge
> >> > > -  * --------------------
> >> > > -  * Must do this prior to any attempt to bind the root device, as the
> >> > > -  * PCI namespace does not get created until this call is made (and
> >> > > -  * thus the root bridge's pci_dev does not exist).
> >> > > -  */
> >> > > - root->bus = pci_acpi_scan_root(root);
> >> > > - if (!root->bus) {
> >> > > -         dev_err(&device->dev,
> >> > > -                 "Bus %04x:%02x not present in PCI namespace\n",
> >> > > -                 root->segment, (unsigned int)root->secondary.start);
> >> > > -         result = -ENODEV;
> >> > > -         goto end;
> >> > > - }
> >> > > -
> >> > > - /* Indicate support for various _OSC capabilities. */
> >> > >   if (pci_ext_cfg_avail())
> >> > >           flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
> >> > >   if (pcie_aspm_support_enabled()) {
> >> > > @@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >> > >                    "(_OSC support mask: 0x%02x)\n", flags);
> >> > >   }
> >> > >
> >> > > + /*
> >> > > +  * TBD: Need PCI interface for enumeration/configuration of roots.
> >> > > +  */
> >> > > +
> >> > > + /*
> >> > > +  * Scan the Root Bridge
> >> > > +  * --------------------
> >> > > +  * Must do this prior to any attempt to bind the root device, as the
> >> > > +  * PCI namespace does not get created until this call is made (and
> >> > > +  * thus the root bridge's pci_dev does not exist).
> >> > > +  */
> >> > > + root->bus = pci_acpi_scan_root(root);
> >> > > + if (!root->bus) {
> >> > > +         dev_err(&device->dev,
> >> > > +                 "Bus %04x:%02x not present in PCI namespace\n",
> >> > > +                 root->segment, (unsigned int)root->secondary.start);
> >> > > +         result = -ENODEV;
> >> > > +         goto end;
> >> > > + }
> >> > > +
> >> > >   pci_acpi_add_bus_pm_notifier(device, root->bus);
> >> > >   if (device->wakeup.flags.run_wake)
> >> > >           device_set_run_wake(root->bus->bridge, true);
> >> > >
> >>
> > --
> > I speak only for myself.
> > Rafael J. Wysocki, Intel Open Source Technology Center.
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Bjorn Helgaas]

On Fri, Aug 23, 2013 at 3:40 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> On Friday, August 23, 2013 02:46:23 PM Bjorn Helgaas wrote:
>> On Fri, Aug 23, 2013 at 2:53 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> > On Friday, August 23, 2013 04:05:11 PM Neil Horman wrote:
>> >> On Fri, Aug 23, 2013 at 09:38:18PM +0200, Rafael J. Wysocki wrote:
>> >> > [CCs added]
>> >> >
>> >> > Please always send PCI-related material to linux-pci in the first place.
>> >> >
>> >> Sorry, I ran get_maintainers and it seemed to think linux-acpi was sufficient.
>> >>
>> >> > The change that broke things for you was actually intentional:
>> >> >
>> >> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
>> >> > Author: Bjorn Helgaas <bhelgaas@google.com>
>> >> > Date:   Mon Apr 1 15:47:39 2013 -0600
>> >> >
>> >> >     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
>> >> >
>> >> >     This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.
>> >> >
>> >> > so I think we'll need to clean up the ASMP initialization after all.
>> >> >
>> >> Crud.  Reading over the revert commit, it seems like the problem boils down to
>> >> the odering of checking aspm_disabled.  It seems to me that the simple fix is to
>> >> track the desire for acpi to disable aspm separately from the users desire to
>> >> disable aspm (aspm_disabled).  Then we just turn the points where we check the
>> >> aspm_disabled into the appropriate or of two variables, except for
>> >> pcie_asmp_sanity_check, which remains sensitive to just the user disable option.
>> >>
>> >> Or is there more to this?
>> >
>> > No, I think you're right.
>> >
>> > Bjorn, what do you think?
>>
>> My opinion is that the _OSC/ASPM state management is ridiculously
>> complicated already, and this would make it slightly more complicated.
>>  That's why my preference would be to attempt a more radical cleanup
>> and simplification instead of adding another wart.
>
> Well, do you have anything specific in mind?

If I had a specific fix in mind, I would just post it, but I've never
had time to work through it all.  What I mean by complicated is that
every time I have to look at ASPM, I have to start by trying to figure
out the relationships between these variables:

    aspm_policy                 # default 0 (POLICY_DEFAULT)
                                  or POLICY_PERFORMANCE
                                  or POLICY_POWERSAVE depending on config
    aspm_disabled               # default 0
    aspm_force                  # default 0
    aspm_support_enabled        # default true

plus the _OSC-related code in acpi_pci_root_add(), which honestly is a
rat's nest.

It sounds like Neil's fix (while probably correct) would tangle that
nest a little more.  But I guess it would make sense to see the actual
patch and the justification (a regression fix, I suppose, but the
details weren't clear to me) before deciding.

>> >> > On Friday, August 23, 2013 01:19:39 PM Neil Horman wrote:
>> >> > > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
>> >> > > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
>> >> > > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
>> >> > > pci_acpi_scan_root before setting the osc flags for the device handle.
>> >> > > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
>> >> > > to determine if a given slot has pcie hotplug capabilties, whcih checks the
>> >> > > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
>> >> > > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
>> >> > > slots are hotplug capable and configures them all to use acpi instead.
>> >> > >
>> >> > > Fix is pretty simple, just defer the scan until after the osc flags have been
>> >> > > set on the device.  Tested by myself and it seems to work well.
>> >> > >
>> >> > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
>> >> > > CC: Len Brown <lenb@kernel.org>
>> >> > > CC: "Rafael J. Wysocki" <rjw@sisk.pl>
>> >> > > CC: linux-acpi@vger.kernel.org
>> >> > > ---
>> >> > >  drivers/acpi/pci_root.c | 41 ++++++++++++++++++++---------------------
>> >> > >  1 file changed, 20 insertions(+), 21 deletions(-)
>> >> > >
>> >> > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> >> > > index 5917839..a2c2661 100644
>> >> > > --- a/drivers/acpi/pci_root.c
>> >> > > +++ b/drivers/acpi/pci_root.c
>> >> > > @@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
>> >> > >   flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
>> >> > >   acpi_pci_osc_support(root, flags);
>> >> > >
>> >> > > - /*
>> >> > > -  * TBD: Need PCI interface for enumeration/configuration of roots.
>> >> > > -  */
>> >> > > -
>> >> > > - /*
>> >> > > -  * Scan the Root Bridge
>> >> > > -  * --------------------
>> >> > > -  * Must do this prior to any attempt to bind the root device, as the
>> >> > > -  * PCI namespace does not get created until this call is made (and
>> >> > > -  * thus the root bridge's pci_dev does not exist).
>> >> > > -  */
>> >> > > - root->bus = pci_acpi_scan_root(root);
>> >> > > - if (!root->bus) {
>> >> > > -         dev_err(&device->dev,
>> >> > > -                 "Bus %04x:%02x not present in PCI namespace\n",
>> >> > > -                 root->segment, (unsigned int)root->secondary.start);
>> >> > > -         result = -ENODEV;
>> >> > > -         goto end;
>> >> > > - }
>> >> > > -
>> >> > > - /* Indicate support for various _OSC capabilities. */
>> >> > >   if (pci_ext_cfg_avail())
>> >> > >           flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>> >> > >   if (pcie_aspm_support_enabled()) {
>> >> > > @@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device,
>> >> > >                    "(_OSC support mask: 0x%02x)\n", flags);
>> >> > >   }
>> >> > >
>> >> > > + /*
>> >> > > +  * TBD: Need PCI interface for enumeration/configuration of roots.
>> >> > > +  */
>> >> > > +
>> >> > > + /*
>> >> > > +  * Scan the Root Bridge
>> >> > > +  * --------------------
>> >> > > +  * Must do this prior to any attempt to bind the root device, as the
>> >> > > +  * PCI namespace does not get created until this call is made (and
>> >> > > +  * thus the root bridge's pci_dev does not exist).
>> >> > > +  */
>> >> > > + root->bus = pci_acpi_scan_root(root);
>> >> > > + if (!root->bus) {
>> >> > > +         dev_err(&device->dev,
>> >> > > +                 "Bus %04x:%02x not present in PCI namespace\n",
>> >> > > +                 root->segment, (unsigned int)root->secondary.start);
>> >> > > +         result = -ENODEV;
>> >> > > +         goto end;
>> >> > > + }
>> >> > > +
>> >> > >   pci_acpi_add_bus_pm_notifier(device, root->bus);
>> >> > >   if (device->wakeup.flags.run_wake)
>> >> > >           device_set_run_wake(root->bus->bridge, true);
>> >> > >
>> >>
>> > --
>> > I speak only for myself.
>> > Rafael J. Wysocki, Intel Open Source Technology Center.
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

On Fri, Aug 23, 2013 at 04:04:59PM -0600, Bjorn Helgaas wrote:
> On Fri, Aug 23, 2013 at 3:40 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > On Friday, August 23, 2013 02:46:23 PM Bjorn Helgaas wrote:
> >> On Fri, Aug 23, 2013 at 2:53 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> >> > On Friday, August 23, 2013 04:05:11 PM Neil Horman wrote:
> >> >> On Fri, Aug 23, 2013 at 09:38:18PM +0200, Rafael J. Wysocki wrote:
> >> >> > [CCs added]
> >> >> >
> >> >> > Please always send PCI-related material to linux-pci in the first place.
> >> >> >
> >> >> Sorry, I ran get_maintainers and it seemed to think linux-acpi was sufficient.
> >> >>
> >> >> > The change that broke things for you was actually intentional:
> >> >> >
> >> >> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> >> >> > Author: Bjorn Helgaas <bhelgaas@google.com>
> >> >> > Date:   Mon Apr 1 15:47:39 2013 -0600
> >> >> >
> >> >> >     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
> >> >> >
> >> >> >     This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.
> >> >> >
> >> >> > so I think we'll need to clean up the ASMP initialization after all.
> >> >> >
> >> >> Crud.  Reading over the revert commit, it seems like the problem boils down to
> >> >> the odering of checking aspm_disabled.  It seems to me that the simple fix is to
> >> >> track the desire for acpi to disable aspm separately from the users desire to
> >> >> disable aspm (aspm_disabled).  Then we just turn the points where we check the
> >> >> aspm_disabled into the appropriate or of two variables, except for
> >> >> pcie_asmp_sanity_check, which remains sensitive to just the user disable option.
> >> >>
> >> >> Or is there more to this?
> >> >
> >> > No, I think you're right.
> >> >
> >> > Bjorn, what do you think?
> >>
> >> My opinion is that the _OSC/ASPM state management is ridiculously
> >> complicated already, and this would make it slightly more complicated.
> >>  That's why my preference would be to attempt a more radical cleanup
> >> and simplification instead of adding another wart.
> >
> > Well, do you have anything specific in mind?
> 
> If I had a specific fix in mind, I would just post it, but I've never
> had time to work through it all.  What I mean by complicated is that
> every time I have to look at ASPM, I have to start by trying to figure
> out the relationships between these variables:
> 
>     aspm_policy                 # default 0 (POLICY_DEFAULT)
>                                   or POLICY_PERFORMANCE
>                                   or POLICY_POWERSAVE depending on config
>     aspm_disabled               # default 0
>     aspm_force                  # default 0
>     aspm_support_enabled        # default true
> 
> plus the _OSC-related code in acpi_pci_root_add(), which honestly is a
> rat's nest.
> 
I agree, I've only looked at it for an hour, and it looks pretty hairy.

> It sounds like Neil's fix (while probably correct) would tangle that
> nest a little more.  But I guess it would make sense to see the actual
No argument, it would add complexity to something thats already very complex.
That said, I think this needs to be fixed.  Currently there are several systems
that are reporting conflicts between ACPI and PCIE hotplug.  While that means
theres lots of griping, theres several people willing to test, so I think we
have an opportunity to fix this.

> patch and the justification (a regression fix, I suppose, but the
> details weren't clear to me) before deciding.
> 
Agreed.  A larger cleanup would be preferable at this point, but I'm not
sufficiently versed in the code to do that right now, so I'll try write an
appropriate for this particular bug, and see what you think on monday.


Regards
Neil

[PATCH v2] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

From: root <root@dhcp47-16.lab.bos.redhat.com>

Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
pci_acpi_scan_root before setting the osc flags for the device handle.
pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
to determine if a given slot has pcie hotplug capabilties, whcih checks the
devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
slots are hotplug capable and configures them all to use acpi instead.

Fix is pretty simple, just defer the scan until after the osc flags have been
set on the device.  Tested by myself and it seems to work well.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Len Brown <lenb@kernel.org>
CC: "Rafael J. Wysocki" <rjw@sisk.pl>
CC: Bjorn Helgaas <bhelgaas@google.com>
CC: linux-acpi@vger.kernel.org
CC: linux-pci@vger.kernel.org

---
Change notes:
v2) eferred the disabling of aspm until after the acpi scan of the pci bus is
complete.  This was done to allow proper handling of pcie 1.1 devices, as per:

commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Mon Apr 1 15:47:39 2013 -0600

    Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"

As discussed previously in the thread the disable logic for aspm needs to be
untangled and refactored, which is not something I'm sufficently versed in teh
hotplug code to do right now, but this fixes the problem above, and prevents the
problem that necessitated the revert without adding any visible complexity to
the user, so I think its ok.
---
 drivers/acpi/pci_root.c | 54 +++++++++++++++++++++++++++++--------------------
 1 file changed, 32 insertions(+), 22 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 5917839..1e80a90 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	struct acpi_pci_root *root;
 	u32 flags, base_flags;
 	acpi_handle handle = device->handle;
+	bool no_aspm = false;
 
 	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 	if (!root)
@@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 	acpi_pci_osc_support(root, flags);
 
-	/*
-	 * TBD: Need PCI interface for enumeration/configuration of roots.
-	 */
-
-	/*
-	 * Scan the Root Bridge
-	 * --------------------
-	 * Must do this prior to any attempt to bind the root device, as the
-	 * PCI namespace does not get created until this call is made (and
-	 * thus the root bridge's pci_dev does not exist).
-	 */
-	root->bus = pci_acpi_scan_root(root);
-	if (!root->bus) {
-		dev_err(&device->dev,
-			"Bus %04x:%02x not present in PCI namespace\n",
-			root->segment, (unsigned int)root->secondary.start);
-		result = -ENODEV;
-		goto end;
-	}
-
-	/* Indicate support for various _OSC capabilities. */
 	if (pci_ext_cfg_avail())
 		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
 	if (pcie_aspm_support_enabled()) {
@@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
 				acpi_format_exception(status), flags);
 			dev_info(&device->dev,
 				 "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
-			pcie_no_aspm();
+			/*
+			 * We want to disable aspm here, but aspm_disabled
+			 * needs to remain in its state from boot so that we
+			 * properly handle pcie 1.1 devices.  So we set this
+			 * flag here, to defer the action until after the acpi
+			 * root scan
+			 */
+			no_aspm = true;
 		}
 	} else {
 		dev_info(&device->dev,
@@ -520,6 +507,29 @@ static int acpi_pci_root_add(struct acpi_device *device,
 			 "(_OSC support mask: 0x%02x)\n", flags);
 	}
 
+	/*
+	 * TBD: Need PCI interface for enumeration/configuration of roots.
+	 */
+
+	/*
+	 * Scan the Root Bridge
+	 * --------------------
+	 * Must do this prior to any attempt to bind the root device, as the
+	 * PCI namespace does not get created until this call is made (and
+	 * thus the root bridge's pci_dev does not exist).
+	 */
+	root->bus = pci_acpi_scan_root(root);
+	if (!root->bus) {
+		dev_err(&device->dev,
+			"Bus %04x:%02x not present in PCI namespace\n",
+			root->segment, (unsigned int)root->secondary.start);
+		result = -ENODEV;
+		goto end;
+	}
+
+	if (no_aspm)
+		pcie_no_aspm();
+
 	pci_acpi_add_bus_pm_notifier(device, root->bus);
 	if (device->wakeup.flags.run_wake)
 		device_set_run_wake(root->bus->bridge, true);
-- 
1.8.1.4

Re: [PATCH v2] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

On Mon, Aug 26, 2013 at 11:36:21AM -0400, Neil Horman wrote:
> From: root <root@dhcp47-16.lab.bos.redhat.com>
> 
> Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> pci_acpi_scan_root before setting the osc flags for the device handle.
> pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> to determine if a given slot has pcie hotplug capabilties, whcih checks the
> devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> slots are hotplug capable and configures them all to use acpi instead.
> 
> Fix is pretty simple, just defer the scan until after the osc flags have been
> set on the device.  Tested by myself and it seems to work well.
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> CC: Len Brown <lenb@kernel.org>
> CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: linux-acpi@vger.kernel.org
> CC: linux-pci@vger.kernel.org
> 
Sorry, self NAK on this, sorry, I forgot to fix up authorship from my
development machine.  I'll resend in a second.
Neil

[PATCH v3] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
pci_acpi_scan_root before setting the osc flags for the device handle.
pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
to determine if a given slot has pcie hotplug capabilties, whcih checks the
devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
slots are hotplug capable and configures them all to use acpi instead.

Fix is pretty simple, just defer the scan until after the osc flags have been
set on the device.  Tested by myself and it seems to work well.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Len Brown <lenb@kernel.org>
CC: "Rafael J. Wysocki" <rjw@sisk.pl>
CC: Bjorn Helgaas <bhelgaas@google.com>
CC: linux-acpi@vger.kernel.org
CC: linux-pci@vger.kernel.org

---
Change notes:
v2) eferred the disabling of aspm until after the acpi scan of the pci bus is
complete.  This was done to allow proper handling of pcie 1.1 devices, as per:

commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Mon Apr 1 15:47:39 2013 -0600

    Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"

As discussed previously in the thread the disable logic for aspm needs to be
untangled and refactored, which is not something I'm sufficently versed in teh
hotplug code to do right now, but this fixes the problem above, and prevents the
problem that necessitated the revert without adding any visible complexity to
the user, so I think its ok.

v3) Fixup stupid authorship error
---
 drivers/acpi/pci_root.c | 54 +++++++++++++++++++++++++++++--------------------
 1 file changed, 32 insertions(+), 22 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 5917839..1e80a90 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	struct acpi_pci_root *root;
 	u32 flags, base_flags;
 	acpi_handle handle = device->handle;
+	bool no_aspm = false;
 
 	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 	if (!root)
@@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 	acpi_pci_osc_support(root, flags);
 
-	/*
-	 * TBD: Need PCI interface for enumeration/configuration of roots.
-	 */
-
-	/*
-	 * Scan the Root Bridge
-	 * --------------------
-	 * Must do this prior to any attempt to bind the root device, as the
-	 * PCI namespace does not get created until this call is made (and
-	 * thus the root bridge's pci_dev does not exist).
-	 */
-	root->bus = pci_acpi_scan_root(root);
-	if (!root->bus) {
-		dev_err(&device->dev,
-			"Bus %04x:%02x not present in PCI namespace\n",
-			root->segment, (unsigned int)root->secondary.start);
-		result = -ENODEV;
-		goto end;
-	}
-
-	/* Indicate support for various _OSC capabilities. */
 	if (pci_ext_cfg_avail())
 		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
 	if (pcie_aspm_support_enabled()) {
@@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
 				acpi_format_exception(status), flags);
 			dev_info(&device->dev,
 				 "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
-			pcie_no_aspm();
+			/*
+			 * We want to disable aspm here, but aspm_disabled
+			 * needs to remain in its state from boot so that we
+			 * properly handle pcie 1.1 devices.  So we set this
+			 * flag here, to defer the action until after the acpi
+			 * root scan
+			 */
+			no_aspm = true;
 		}
 	} else {
 		dev_info(&device->dev,
@@ -520,6 +507,29 @@ static int acpi_pci_root_add(struct acpi_device *device,
 			 "(_OSC support mask: 0x%02x)\n", flags);
 	}
 
+	/*
+	 * TBD: Need PCI interface for enumeration/configuration of roots.
+	 */
+
+	/*
+	 * Scan the Root Bridge
+	 * --------------------
+	 * Must do this prior to any attempt to bind the root device, as the
+	 * PCI namespace does not get created until this call is made (and
+	 * thus the root bridge's pci_dev does not exist).
+	 */
+	root->bus = pci_acpi_scan_root(root);
+	if (!root->bus) {
+		dev_err(&device->dev,
+			"Bus %04x:%02x not present in PCI namespace\n",
+			root->segment, (unsigned int)root->secondary.start);
+		result = -ENODEV;
+		goto end;
+	}
+
+	if (no_aspm)
+		pcie_no_aspm();
+
 	pci_acpi_add_bus_pm_notifier(device, root->bus);
 	if (device->wakeup.flags.run_wake)
 		device_set_run_wake(root->bus->bridge, true);
-- 
1.8.1.4

Re: [PATCH v3] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Bjorn Helgaas]

[+cc Stefan]

On Mon, Aug 26, 2013 at 9:39 AM, Neil Horman <nhorman@tuxdriver.com> wrote:
> Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> pci_acpi_scan_root before setting the osc flags for the device handle.
> pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> to determine if a given slot has pcie hotplug capabilties, whcih checks the
> devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> slots are hotplug capable and configures them all to use acpi instead.

I'd like to make it more explicit what we're fixing.  Apparently this
is a regression between v3.9 and v3.10.

Is this a fix for problems like
https://bugzilla.kernel.org/show_bug.cgi?id=60736 ?  That bug is that
an ExpressCard slot doesn't work unless we boot with
"acpiphp.disable=1".  I think what happens there is that acpiphp
claims the slot before we run _OSC, so pciehp doesn't claim it, even
though _OSC did grant us control over native PCIe hotplug.

> Fix is pretty simple, just defer the scan until after the osc flags have been
> set on the device.  Tested by myself and it seems to work well.
>
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> CC: Len Brown <lenb@kernel.org>
> CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: linux-acpi@vger.kernel.org
> CC: linux-pci@vger.kernel.org
>
> ---
> Change notes:
> v2) eferred the disabling of aspm until after the acpi scan of the pci bus is
> complete.  This was done to allow proper handling of pcie 1.1 devices, as per:
>
> commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> Author: Bjorn Helgaas <bhelgaas@google.com>
> Date:   Mon Apr 1 15:47:39 2013 -0600
>
>     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
>
> As discussed previously in the thread the disable logic for aspm needs to be
> untangled and refactored, which is not something I'm sufficently versed in teh
> hotplug code to do right now, but this fixes the problem above, and prevents the
> problem that necessitated the revert without adding any visible complexity to
> the user, so I think its ok.
>
> v3) Fixup stupid authorship error
> ---
>  drivers/acpi/pci_root.c | 54 +++++++++++++++++++++++++++++--------------------
>  1 file changed, 32 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 5917839..1e80a90 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>         struct acpi_pci_root *root;
>         u32 flags, base_flags;
>         acpi_handle handle = device->handle;
> +       bool no_aspm = false;
>
>         root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
>         if (!root)
> @@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
>         flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
>         acpi_pci_osc_support(root, flags);
>
> -       /*
> -        * TBD: Need PCI interface for enumeration/configuration of roots.
> -        */
> -
> -       /*
> -        * Scan the Root Bridge
> -        * --------------------
> -        * Must do this prior to any attempt to bind the root device, as the
> -        * PCI namespace does not get created until this call is made (and
> -        * thus the root bridge's pci_dev does not exist).
> -        */
> -       root->bus = pci_acpi_scan_root(root);
> -       if (!root->bus) {
> -               dev_err(&device->dev,
> -                       "Bus %04x:%02x not present in PCI namespace\n",
> -                       root->segment, (unsigned int)root->secondary.start);
> -               result = -ENODEV;
> -               goto end;
> -       }
> -
> -       /* Indicate support for various _OSC capabilities. */
>         if (pci_ext_cfg_avail())
>                 flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>         if (pcie_aspm_support_enabled()) {
> @@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                                 acpi_format_exception(status), flags);
>                         dev_info(&device->dev,
>                                  "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
> -                       pcie_no_aspm();
> +                       /*
> +                        * We want to disable aspm here, but aspm_disabled
> +                        * needs to remain in its state from boot so that we
> +                        * properly handle pcie 1.1 devices.  So we set this
> +                        * flag here, to defer the action until after the acpi
> +                        * root scan
> +                        */
> +                       no_aspm = true;
>                 }
>         } else {
>                 dev_info(&device->dev,
> @@ -520,6 +507,29 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                          "(_OSC support mask: 0x%02x)\n", flags);
>         }
>
> +       /*
> +        * TBD: Need PCI interface for enumeration/configuration of roots.
> +        */
> +
> +       /*
> +        * Scan the Root Bridge
> +        * --------------------
> +        * Must do this prior to any attempt to bind the root device, as the
> +        * PCI namespace does not get created until this call is made (and
> +        * thus the root bridge's pci_dev does not exist).
> +        */
> +       root->bus = pci_acpi_scan_root(root);
> +       if (!root->bus) {
> +               dev_err(&device->dev,
> +                       "Bus %04x:%02x not present in PCI namespace\n",
> +                       root->segment, (unsigned int)root->secondary.start);
> +               result = -ENODEV;
> +               goto end;
> +       }
> +
> +       if (no_aspm)
> +               pcie_no_aspm();
> +
>         pci_acpi_add_bus_pm_notifier(device, root->bus);
>         if (device->wakeup.flags.run_wake)
>                 device_set_run_wake(root->bus->bridge, true);
> --
> 1.8.1.4
>

Re: [PATCH v3] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

On Tue, Aug 27, 2013 at 03:34:11PM -0600, Bjorn Helgaas wrote:
> [+cc Stefan]
> 
> On Mon, Aug 26, 2013 at 9:39 AM, Neil Horman <nhorman@tuxdriver.com> wrote:
> > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> > pci_acpi_scan_root before setting the osc flags for the device handle.
> > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> > to determine if a given slot has pcie hotplug capabilties, whcih checks the
> > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> > slots are hotplug capable and configures them all to use acpi instead.
> 
> I'd like to make it more explicit what we're fixing.  Apparently this
> is a regression between v3.9 and v3.10.
> 
> Is this a fix for problems like
> https://bugzilla.kernel.org/show_bug.cgi?id=60736 ?  That bug is that
> an ExpressCard slot doesn't work unless we boot with
> "acpiphp.disable=1".  I think what happens there is that acpiphp
> claims the slot before we run _OSC, so pciehp doesn't claim it, even
> though _OSC did grant us control over native PCIe hotplug.
> 
Yes, that bug is precisely what I am trying to fix (although your wording above is
inverted from the problem in the bug).  What happens is that acpiphp claims the
pcie ports, because acpiphp init runs first, and we haven't yet parsed _OSC,
which would have told acpiphp to yield control to pciehp.  The initial fix I
proposed fixed this by parsing _OSC prior to running the acpiphp bus scan, but
that reintroduced the problem of not handling pcie 1.1 aspm properly.  That has
been fixed in v2/v3 by deferring the setting of aspm_disable until after the bus
scan.

Shall I submit a v4 with an updated changelog?

Best
Neil

Re: [PATCH v3] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Bjorn Helgaas]

On Tue, Aug 27, 2013 at 5:43 PM, Neil Horman <nhorman@tuxdriver.com> wrote:
> On Tue, Aug 27, 2013 at 03:34:11PM -0600, Bjorn Helgaas wrote:
>> [+cc Stefan]
>>
>> On Mon, Aug 26, 2013 at 9:39 AM, Neil Horman <nhorman@tuxdriver.com> wrote:
>> > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
>> > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
>> > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
>> > pci_acpi_scan_root before setting the osc flags for the device handle.
>> > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
>> > to determine if a given slot has pcie hotplug capabilties, whcih checks the
>> > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
>> > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
>> > slots are hotplug capable and configures them all to use acpi instead.
>>
>> I'd like to make it more explicit what we're fixing.  Apparently this
>> is a regression between v3.9 and v3.10.
>>
>> Is this a fix for problems like
>> https://bugzilla.kernel.org/show_bug.cgi?id=60736 ?  That bug is that
>> an ExpressCard slot doesn't work unless we boot with
>> "acpiphp.disable=1".  I think what happens there is that acpiphp
>> claims the slot before we run _OSC, so pciehp doesn't claim it, even
>> though _OSC did grant us control over native PCIe hotplug.
>>
> Yes, that bug is precisely what I am trying to fix (although your wording above is
> inverted from the problem in the bug).  What happens is that acpiphp claims the
> pcie ports, because acpiphp init runs first, and we haven't yet parsed _OSC,
> which would have told acpiphp to yield control to pciehp.  The initial fix I
> proposed fixed this by parsing _OSC prior to running the acpiphp bus scan, but
> that reintroduced the problem of not handling pcie 1.1 aspm properly.  That has
> been fixed in v2/v3 by deferring the setting of aspm_disable until after the bus
> scan.
>
> Shall I submit a v4 with an updated changelog?

No need, I'll update the changelog and include the bugzilla reference
and post it for your approval.  Thanks!

Bjorn

Re: [PATCH v3] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

On Wed, Aug 28, 2013 at 07:04:47AM -0600, Bjorn Helgaas wrote:
> On Tue, Aug 27, 2013 at 5:43 PM, Neil Horman <nhorman@tuxdriver.com> wrote:
> > On Tue, Aug 27, 2013 at 03:34:11PM -0600, Bjorn Helgaas wrote:
> >> [+cc Stefan]
> >>
> >> On Mon, Aug 26, 2013 at 9:39 AM, Neil Horman <nhorman@tuxdriver.com> wrote:
> >> > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> >> > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> >> > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> >> > pci_acpi_scan_root before setting the osc flags for the device handle.
> >> > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> >> > to determine if a given slot has pcie hotplug capabilties, whcih checks the
> >> > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> >> > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> >> > slots are hotplug capable and configures them all to use acpi instead.
> >>
> >> I'd like to make it more explicit what we're fixing.  Apparently this
> >> is a regression between v3.9 and v3.10.
> >>
> >> Is this a fix for problems like
> >> https://bugzilla.kernel.org/show_bug.cgi?id=60736 ?  That bug is that
> >> an ExpressCard slot doesn't work unless we boot with
> >> "acpiphp.disable=1".  I think what happens there is that acpiphp
> >> claims the slot before we run _OSC, so pciehp doesn't claim it, even
> >> though _OSC did grant us control over native PCIe hotplug.
> >>
> > Yes, that bug is precisely what I am trying to fix (although your wording above is
> > inverted from the problem in the bug).  What happens is that acpiphp claims the
> > pcie ports, because acpiphp init runs first, and we haven't yet parsed _OSC,
> > which would have told acpiphp to yield control to pciehp.  The initial fix I
> > proposed fixed this by parsing _OSC prior to running the acpiphp bus scan, but
> > that reintroduced the problem of not handling pcie 1.1 aspm properly.  That has
> > been fixed in v2/v3 by deferring the setting of aspm_disable until after the bus
> > scan.
> >
> > Shall I submit a v4 with an updated changelog?
> 
> No need, I'll update the changelog and include the bugzilla reference
> and post it for your approval.  Thanks!
> 
> Bjorn
> 
Great, thanks!
Neil

Re: [PATCH v3] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Bjorn Helgaas]

On Mon, Aug 26, 2013 at 11:39:13AM -0400, Neil Horman wrote:
> Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> pci_acpi_scan_root before setting the osc flags for the device handle.
> pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> to determine if a given slot has pcie hotplug capabilties, whcih checks the
> devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> slots are hotplug capable and configures them all to use acpi instead.
> 
> Fix is pretty simple, just defer the scan until after the osc flags have been
> set on the device.  Tested by myself and it seems to work well.
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> CC: Len Brown <lenb@kernel.org>
> CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: linux-acpi@vger.kernel.org
> CC: linux-pci@vger.kernel.org
> 
> ---
> Change notes:
> v2) eferred the disabling of aspm until after the acpi scan of the pci bus is
> complete.  This was done to allow proper handling of pcie 1.1 devices, as per:
> 
> commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> Author: Bjorn Helgaas <bhelgaas@google.com>
> Date:   Mon Apr 1 15:47:39 2013 -0600
> 
>     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
> 
> As discussed previously in the thread the disable logic for aspm needs to be
> untangled and refactored, which is not something I'm sufficently versed in teh
> hotplug code to do right now, but this fixes the problem above, and prevents the
> problem that necessitated the revert without adding any visible complexity to
> the user, so I think its ok.
> 
> v3) Fixup stupid authorship error
> ---
>  drivers/acpi/pci_root.c | 54 +++++++++++++++++++++++++++++--------------------
>  1 file changed, 32 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 5917839..1e80a90 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	struct acpi_pci_root *root;
>  	u32 flags, base_flags;
>  	acpi_handle handle = device->handle;
> +	bool no_aspm = false;
>  
>  	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
>  	if (!root)
> @@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
>  	acpi_pci_osc_support(root, flags);
>  
> -	/*
> -	 * TBD: Need PCI interface for enumeration/configuration of roots.
> -	 */
> -
> -	/*
> -	 * Scan the Root Bridge
> -	 * --------------------
> -	 * Must do this prior to any attempt to bind the root device, as the
> -	 * PCI namespace does not get created until this call is made (and
> -	 * thus the root bridge's pci_dev does not exist).
> -	 */
> -	root->bus = pci_acpi_scan_root(root);
> -	if (!root->bus) {
> -		dev_err(&device->dev,
> -			"Bus %04x:%02x not present in PCI namespace\n",
> -			root->segment, (unsigned int)root->secondary.start);
> -		result = -ENODEV;
> -		goto end;
> -	}
> -
> -	/* Indicate support for various _OSC capabilities. */
>  	if (pci_ext_cfg_avail())
>  		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>  	if (pcie_aspm_support_enabled()) {
> @@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  				acpi_format_exception(status), flags);
>  			dev_info(&device->dev,
>  				 "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
> -			pcie_no_aspm();
> +			/*
> +			 * We want to disable aspm here, but aspm_disabled
> +			 * needs to remain in its state from boot so that we
> +			 * properly handle pcie 1.1 devices.  So we set this
> +			 * flag here, to defer the action until after the acpi
> +			 * root scan
> +			 */
> +			no_aspm = true;
>  		}
>  	} else {
>  		dev_info(&device->dev,
> @@ -520,6 +507,29 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  			 "(_OSC support mask: 0x%02x)\n", flags);
>  	}
>  
> +	/*
> +	 * TBD: Need PCI interface for enumeration/configuration of roots.
> +	 */
> +
> +	/*
> +	 * Scan the Root Bridge
> +	 * --------------------
> +	 * Must do this prior to any attempt to bind the root device, as the
> +	 * PCI namespace does not get created until this call is made (and
> +	 * thus the root bridge's pci_dev does not exist).
> +	 */
> +	root->bus = pci_acpi_scan_root(root);
> +	if (!root->bus) {
> +		dev_err(&device->dev,
> +			"Bus %04x:%02x not present in PCI namespace\n",
> +			root->segment, (unsigned int)root->secondary.start);
> +		result = -ENODEV;
> +		goto end;
> +	}
> +
> +	if (no_aspm)
> +		pcie_no_aspm();
> +
>  	pci_acpi_add_bus_pm_notifier(device, root->bus);
>  	if (device->wakeup.flags.run_wake)
>  		device_set_run_wake(root->bus->bridge, true);

I think there are two problems with this patch:

  1) There's another call of pcie_no_aspm() at line 454 (in the
  error path when acpi_pci_osc_support() fails), which happens
  before scanning the bus.  I think this needs to be converted to
  "no_aspm = true" as you did for the one in the error path when
  acpi_pci_osc_control_set() fails.

  2) You effectively moved the call of "pcie_clear_aspm(root->bus)"
  so it now happens before scanning the bus, which will cause a
  NULL pointer dereference if we take that path.

I think we need something like the patch below on top of your
v3 patch.  Can you take a look and see if this makes sense, and
if so, update your patch to include these or similar fixes?

Here are my notes about where the ASPM and root->osc_control_set 
setting and testing happen.

Before your patch:

    acpi_pci_root_add
      root = kzalloc			# root->osc_control_set = 0
      acpi_pci_osc_support		# indicate OS support for segments
      root->bus = pci_acpi_scan_root	# SCAN BUS
	pci_create_root_bus
	  pcibios_add_bus
	    acpi_pci_add_bus
	      acpiphp_enumerate_slots
		acpi_walk_namespace(..., register_slot, ...)
		  register_slot
		    device_is_managed_by_native_pciehp
		      <test root->osc_control_set>	# root->osc_control_set == 0
		    return if OS has PCIe hotplug control (we never do)
		    acpiphp_register_hotplug_slot (so we always do this)
      acpi_pci_osc_support		# indicate OS support for MSI, ASPM, etc
      if (_osc_support() failed)
	pci_no_aspm
      acpi_pci_osc_control_set		# request OS control of hotplug, PME, AER, etc
	root->osc_control_set = XX
      if (_osc_control_set() succeeded) {
	if (FADT NO_ASPM bit)
	  pcie_clear_aspm
	    list_for_each_entry(..., &bus->devices, ...)
      } else
	pcie_no_aspm			# _osc_control_set() failed

After your patch:

    acpi_pci_root_add
      root = kzalloc			# root->osc_control_set = 0
      acpi_pci_osc_support		# indicate OS support for segments
      if (_osc_support() failed)
	pci_no_aspm			# ** (1) before bus scan
      acpi_pci_osc_support		# indicate OS support for MSI, ASPM, etc
      acpi_pci_osc_control_set		# request OS control of hotplug, PME, AER, etc
	root->osc_control_set = XX
      if (_osc_control_set() succeeded) {
	if (FADT NO_ASPM bit)
	  pcie_clear_aspm(root->bus)	# ** (2) root->bus == NULL
	    list_for_each_entry(..., &bus->devices, ...)
      } else
	no_aspm = true			# _osc_control_set() failed
      root->bus = pci_acpi_scan_root	# SCAN BUS
	pci_create_root_bus
	  pcibios_add_bus
	    acpi_pci_add_bus
	      acpiphp_enumerate_slots
		acpi_walk_namespace(..., register_slot, ...)
		  register_slot
		    device_is_managed_by_native_pciehp
		      <test root->osc_control_set>
		    return if OS has PCIe hotplug control
		    acpiphp_register_hotplug_slot
      if (no_aspm)
	pcie_no_aspm


Bjorn


diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index a37a372..a67853e 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -378,7 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	struct acpi_pci_root *root;
 	u32 flags, base_flags;
 	acpi_handle handle = device->handle;
-	bool no_aspm = false;
+	bool no_aspm = false, clear_aspm = false;
 
 	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 	if (!root)
@@ -451,7 +451,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 		if (ACPI_FAILURE(status)) {
 			dev_info(&device->dev, "ACPI _OSC support "
 				"notification failed, disabling PCIe ASPM\n");
-			pcie_no_aspm();
+			no_aspm = true;
 			flags = base_flags;
 		}
 	}
@@ -483,7 +483,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 				 * We have ASPM control, but the FADT indicates
 				 * that it's unsupported. Clear it.
 				 */
-				pcie_clear_aspm(root->bus);
+				clear_aspm = true;
 			}
 		} else {
 			dev_info(&device->dev,
@@ -527,6 +527,10 @@ static int acpi_pci_root_add(struct acpi_device *device,
 		goto end;
 	}
 
+	if (clear_aspm) {
+		dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
+		pcie_clear_aspm(root->bus);
+	}
 	if (no_aspm)
 		pcie_no_aspm();
 

Re: [PATCH v3] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

On Thu, Aug 29, 2013 at 11:47:13AM -0600, Bjorn Helgaas wrote:
> On Mon, Aug 26, 2013 at 11:39:13AM -0400, Neil Horman wrote:
> > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed
> > slots for hotplug capabilites got reversed.  While this isn't a big deal, it did
> > uncover a bug in the ACPI bus setup path.  Specifically, acpi_pci_root_add calls
> > pci_acpi_scan_root before setting the osc flags for the device handle.
> > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp()
> > to determine if a given slot has pcie hotplug capabilties, whcih checks the
> > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag.  Since that flag is not set
> > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie
> > slots are hotplug capable and configures them all to use acpi instead.
> > 
> > Fix is pretty simple, just defer the scan until after the osc flags have been
> > set on the device.  Tested by myself and it seems to work well.
> > 
> > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > CC: Len Brown <lenb@kernel.org>
> > CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> > CC: Bjorn Helgaas <bhelgaas@google.com>
> > CC: linux-acpi@vger.kernel.org
> > CC: linux-pci@vger.kernel.org
> > 
> > ---
> > Change notes:
> > v2) eferred the disabling of aspm until after the acpi scan of the pci bus is
> > complete.  This was done to allow proper handling of pcie 1.1 devices, as per:
> > 
> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> > Author: Bjorn Helgaas <bhelgaas@google.com>
> > Date:   Mon Apr 1 15:47:39 2013 -0600
> > 
> >     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
> > 
> > As discussed previously in the thread the disable logic for aspm needs to be
> > untangled and refactored, which is not something I'm sufficently versed in teh
> > hotplug code to do right now, but this fixes the problem above, and prevents the
> > problem that necessitated the revert without adding any visible complexity to
> > the user, so I think its ok.
> > 
> > v3) Fixup stupid authorship error
> > ---
> >  drivers/acpi/pci_root.c | 54 +++++++++++++++++++++++++++++--------------------
> >  1 file changed, 32 insertions(+), 22 deletions(-)
> > 
> > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > index 5917839..1e80a90 100644
> > --- a/drivers/acpi/pci_root.c
> > +++ b/drivers/acpi/pci_root.c
> > @@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >  	struct acpi_pci_root *root;
> >  	u32 flags, base_flags;
> >  	acpi_handle handle = device->handle;
> > +	bool no_aspm = false;
> >  
> >  	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
> >  	if (!root)
> > @@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >  	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
> >  	acpi_pci_osc_support(root, flags);
> >  
> > -	/*
> > -	 * TBD: Need PCI interface for enumeration/configuration of roots.
> > -	 */
> > -
> > -	/*
> > -	 * Scan the Root Bridge
> > -	 * --------------------
> > -	 * Must do this prior to any attempt to bind the root device, as the
> > -	 * PCI namespace does not get created until this call is made (and
> > -	 * thus the root bridge's pci_dev does not exist).
> > -	 */
> > -	root->bus = pci_acpi_scan_root(root);
> > -	if (!root->bus) {
> > -		dev_err(&device->dev,
> > -			"Bus %04x:%02x not present in PCI namespace\n",
> > -			root->segment, (unsigned int)root->secondary.start);
> > -		result = -ENODEV;
> > -		goto end;
> > -	}
> > -
> > -	/* Indicate support for various _OSC capabilities. */
> >  	if (pci_ext_cfg_avail())
> >  		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
> >  	if (pcie_aspm_support_enabled()) {
> > @@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >  				acpi_format_exception(status), flags);
> >  			dev_info(&device->dev,
> >  				 "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
> > -			pcie_no_aspm();
> > +			/*
> > +			 * We want to disable aspm here, but aspm_disabled
> > +			 * needs to remain in its state from boot so that we
> > +			 * properly handle pcie 1.1 devices.  So we set this
> > +			 * flag here, to defer the action until after the acpi
> > +			 * root scan
> > +			 */
> > +			no_aspm = true;
> >  		}
> >  	} else {
> >  		dev_info(&device->dev,
> > @@ -520,6 +507,29 @@ static int acpi_pci_root_add(struct acpi_device *device,
> >  			 "(_OSC support mask: 0x%02x)\n", flags);
> >  	}
> >  
> > +	/*
> > +	 * TBD: Need PCI interface for enumeration/configuration of roots.
> > +	 */
> > +
> > +	/*
> > +	 * Scan the Root Bridge
> > +	 * --------------------
> > +	 * Must do this prior to any attempt to bind the root device, as the
> > +	 * PCI namespace does not get created until this call is made (and
> > +	 * thus the root bridge's pci_dev does not exist).
> > +	 */
> > +	root->bus = pci_acpi_scan_root(root);
> > +	if (!root->bus) {
> > +		dev_err(&device->dev,
> > +			"Bus %04x:%02x not present in PCI namespace\n",
> > +			root->segment, (unsigned int)root->secondary.start);
> > +		result = -ENODEV;
> > +		goto end;
> > +	}
> > +
> > +	if (no_aspm)
> > +		pcie_no_aspm();
> > +
> >  	pci_acpi_add_bus_pm_notifier(device, root->bus);
> >  	if (device->wakeup.flags.run_wake)
> >  		device_set_run_wake(root->bus->bridge, true);
> 
> I think there are two problems with this patch:
> 
>   1) There's another call of pcie_no_aspm() at line 454 (in the
>   error path when acpi_pci_osc_support() fails), which happens
>   before scanning the bus.  I think this needs to be converted to
>   "no_aspm = true" as you did for the one in the error path when
>   acpi_pci_osc_control_set() fails.
> 
I was wondering about that.  I left it alone because this patch didn't introduce
that condition (callingpcie_no_aspm at line 454).  I thought perhaps there was
something there I didn't completely understand, but yes, I agree, it seems like
it should use the no_aspm just like the call I converted.

>   2) You effectively moved the call of "pcie_clear_aspm(root->bus)"
>   so it now happens before scanning the bus, which will cause a
>   NULL pointer dereference if we take that path.
> 
Yes, you're correct, and I missed that, we need to defer that call just like we
do with pcie_no_aspm.


> I think we need something like the patch below on top of your
> v3 patch.  Can you take a look and see if this makes sense, and
> if so, update your patch to include these or similar fixes?
> 
I agree, I'll send a v4 tomorrow, with these changes incorporated, and an
updated changelog reflecting the exact problem we're solving here.

Thanks!
Neil

> Here are my notes about where the ASPM and root->osc_control_set 
> setting and testing happen.
> 
> Before your patch:
> 
>     acpi_pci_root_add
>       root = kzalloc			# root->osc_control_set = 0
>       acpi_pci_osc_support		# indicate OS support for segments
>       root->bus = pci_acpi_scan_root	# SCAN BUS
> 	pci_create_root_bus
> 	  pcibios_add_bus
> 	    acpi_pci_add_bus
> 	      acpiphp_enumerate_slots
> 		acpi_walk_namespace(..., register_slot, ...)
> 		  register_slot
> 		    device_is_managed_by_native_pciehp
> 		      <test root->osc_control_set>	# root->osc_control_set == 0
> 		    return if OS has PCIe hotplug control (we never do)
> 		    acpiphp_register_hotplug_slot (so we always do this)
>       acpi_pci_osc_support		# indicate OS support for MSI, ASPM, etc
>       if (_osc_support() failed)
> 	pci_no_aspm
>       acpi_pci_osc_control_set		# request OS control of hotplug, PME, AER, etc
> 	root->osc_control_set = XX
>       if (_osc_control_set() succeeded) {
> 	if (FADT NO_ASPM bit)
> 	  pcie_clear_aspm
> 	    list_for_each_entry(..., &bus->devices, ...)
>       } else
> 	pcie_no_aspm			# _osc_control_set() failed
> 
> After your patch:
> 
>     acpi_pci_root_add
>       root = kzalloc			# root->osc_control_set = 0
>       acpi_pci_osc_support		# indicate OS support for segments
>       if (_osc_support() failed)
> 	pci_no_aspm			# ** (1) before bus scan
>       acpi_pci_osc_support		# indicate OS support for MSI, ASPM, etc
>       acpi_pci_osc_control_set		# request OS control of hotplug, PME, AER, etc
> 	root->osc_control_set = XX
>       if (_osc_control_set() succeeded) {
> 	if (FADT NO_ASPM bit)
> 	  pcie_clear_aspm(root->bus)	# ** (2) root->bus == NULL
> 	    list_for_each_entry(..., &bus->devices, ...)
>       } else
> 	no_aspm = true			# _osc_control_set() failed
>       root->bus = pci_acpi_scan_root	# SCAN BUS
> 	pci_create_root_bus
> 	  pcibios_add_bus
> 	    acpi_pci_add_bus
> 	      acpiphp_enumerate_slots
> 		acpi_walk_namespace(..., register_slot, ...)
> 		  register_slot
> 		    device_is_managed_by_native_pciehp
> 		      <test root->osc_control_set>
> 		    return if OS has PCIe hotplug control
> 		    acpiphp_register_hotplug_slot
>       if (no_aspm)
> 	pcie_no_aspm
> 
> 
> Bjorn
> 
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index a37a372..a67853e 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -378,7 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	struct acpi_pci_root *root;
>  	u32 flags, base_flags;
>  	acpi_handle handle = device->handle;
> -	bool no_aspm = false;
> +	bool no_aspm = false, clear_aspm = false;
>  
>  	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
>  	if (!root)
> @@ -451,7 +451,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  		if (ACPI_FAILURE(status)) {
>  			dev_info(&device->dev, "ACPI _OSC support "
>  				"notification failed, disabling PCIe ASPM\n");
> -			pcie_no_aspm();
> +			no_aspm = true;
>  			flags = base_flags;
>  		}
>  	}
> @@ -483,7 +483,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  				 * We have ASPM control, but the FADT indicates
>  				 * that it's unsupported. Clear it.
>  				 */
> -				pcie_clear_aspm(root->bus);
> +				clear_aspm = true;
>  			}
>  		} else {
>  			dev_info(&device->dev,
> @@ -527,6 +527,10 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  		goto end;
>  	}
>  
> +	if (clear_aspm) {
> +		dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
> +		pcie_clear_aspm(root->bus);
> +	}
>  	if (no_aspm)
>  		pcie_no_aspm();
>  
> 

[PATCH v4] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

This is a fix for:
https://bugzilla.kernel.org/show_bug.cgi?id=60736

During the 3.8 devel cycle:

commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6
Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
Date:   Tue Oct 30 15:27:13 2012 +0900

    PCI/ACPI: Request _OSC control before scanning PCI root bus

went in to allow us to query the pcie hotplug flags during the acpi bus scan.
It however caused problems with the disabling of pcie aspm, and so:
commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Mon Apr 1 15:47:39 2013 -0600

    Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"

Backed it out.  This of course brought back the problem in which acpi took over
hotplug ports that were meant to be controlled by pcie.

This patch gives us both items.  It lets us request _OSC control before scanning
the pci root bus, but defers any disabling of aspm until after the scan is
complete, allowing us to properly handle old pcie 1.1 devices aspm settings
properly, as b8178f130e documents.

Tested successfully by myself.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Len Brown <lenb@kernel.org>
CC: "Rafael J. Wysocki" <rjw@sisk.pl>
CC: linux-acpi@vger.kernel.org
CC: linux-pci@vger.kernel.org
---
 drivers/acpi/pci_root.c | 62 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 38 insertions(+), 24 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 5917839..6110fd2 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	struct acpi_pci_root *root;
 	u32 flags, base_flags;
 	acpi_handle handle = device->handle;
+	bool no_aspm = false, clear_aspm = false;
 
 	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 	if (!root)
@@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 	acpi_pci_osc_support(root, flags);
 
-	/*
-	 * TBD: Need PCI interface for enumeration/configuration of roots.
-	 */
-
-	/*
-	 * Scan the Root Bridge
-	 * --------------------
-	 * Must do this prior to any attempt to bind the root device, as the
-	 * PCI namespace does not get created until this call is made (and
-	 * thus the root bridge's pci_dev does not exist).
-	 */
-	root->bus = pci_acpi_scan_root(root);
-	if (!root->bus) {
-		dev_err(&device->dev,
-			"Bus %04x:%02x not present in PCI namespace\n",
-			root->segment, (unsigned int)root->secondary.start);
-		result = -ENODEV;
-		goto end;
-	}
-
-	/* Indicate support for various _OSC capabilities. */
 	if (pci_ext_cfg_avail())
 		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
 	if (pcie_aspm_support_enabled()) {
@@ -471,7 +451,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 		if (ACPI_FAILURE(status)) {
 			dev_info(&device->dev, "ACPI _OSC support "
 				"notification failed, disabling PCIe ASPM\n");
-			pcie_no_aspm();
+			no_aspm = true;
 			flags = base_flags;
 		}
 	}
@@ -503,7 +483,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 				 * We have ASPM control, but the FADT indicates
 				 * that it's unsupported. Clear it.
 				 */
-				pcie_clear_aspm(root->bus);
+				clear_aspm = true;
 			}
 		} else {
 			dev_info(&device->dev,
@@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
 				acpi_format_exception(status), flags);
 			dev_info(&device->dev,
 				 "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
-			pcie_no_aspm();
+			/*
+			 * We want to disable aspm here, but aspm_disabled 
+			 * needs to remain in its state from boot so that we
+			 * properly handle pcie 1.1 devices.  So we set this
+			 * flag here, to defer the action until after the acpi
+			 * root scan
+			 */
+			no_aspm = true;
 		}
 	} else {
 		dev_info(&device->dev,
@@ -520,6 +507,33 @@ static int acpi_pci_root_add(struct acpi_device *device,
 			 "(_OSC support mask: 0x%02x)\n", flags);
 	}
 
+	/*
+	 * TBD: Need PCI interface for enumeration/configuration of roots.
+	 */
+
+	/*
+	 * Scan the Root Bridge
+	 * --------------------
+	 * Must do this prior to any attempt to bind the root device, as the
+	 * PCI namespace does not get created until this call is made (and
+	 * thus the root bridge's pci_dev does not exist).
+	 */
+	root->bus = pci_acpi_scan_root(root);
+	if (!root->bus) {
+		dev_err(&device->dev,
+			"Bus %04x:%02x not present in PCI namespace\n",
+			root->segment, (unsigned int)root->secondary.start);
+		result = -ENODEV;
+		goto end;
+	}
+
+	if (clear_aspm) {
+		dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
+		pcie_clear_aspm(root->bus);
+	}
+	if (no_aspm)
+		pcie_no_aspm();
+
 	pci_acpi_add_bus_pm_notifier(device, root->bus);
 	if (device->wakeup.flags.run_wake)
 		device_set_run_wake(root->bus->bridge, true);
-- 
1.8.1.4

Re: [PATCH v4] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Yinghai Lu]

On Thu, Aug 29, 2013 at 1:17 PM, Neil Horman <nhorman@tuxdriver.com> wrote:
> This is a fix for:
> https://bugzilla.kernel.org/show_bug.cgi?id=60736
>
> During the 3.8 devel cycle:
>
> commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6
> Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
> Date:   Tue Oct 30 15:27:13 2012 +0900
>
>     PCI/ACPI: Request _OSC control before scanning PCI root bus
>
> went in to allow us to query the pcie hotplug flags during the acpi bus scan.
> It however caused problems with the disabling of pcie aspm, and so:
> commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> Author: Bjorn Helgaas <bhelgaas@google.com>
> Date:   Mon Apr 1 15:47:39 2013 -0600
>
>     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
>
> Backed it out.  This of course brought back the problem in which acpi took over
> hotplug ports that were meant to be controlled by pcie.
>
> This patch gives us both items.  It lets us request _OSC control before scanning
> the pci root bus, but defers any disabling of aspm until after the scan is
> complete, allowing us to properly handle old pcie 1.1 devices aspm settings
> properly, as b8178f130e documents.
>
> Tested successfully by myself.
>
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> CC: Len Brown <lenb@kernel.org>
> CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> CC: linux-acpi@vger.kernel.org
> CC: linux-pci@vger.kernel.org
> ---
>  drivers/acpi/pci_root.c | 62 ++++++++++++++++++++++++++++++-------------------
>  1 file changed, 38 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 5917839..6110fd2 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>         struct acpi_pci_root *root;
>         u32 flags, base_flags;
>         acpi_handle handle = device->handle;
> +       bool no_aspm = false, clear_aspm = false;
>
>         root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
>         if (!root)
> @@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
>         flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
>         acpi_pci_osc_support(root, flags);
>
> -       /*
> -        * TBD: Need PCI interface for enumeration/configuration of roots.
> -        */
> -
> -       /*
> -        * Scan the Root Bridge
> -        * --------------------
> -        * Must do this prior to any attempt to bind the root device, as the
> -        * PCI namespace does not get created until this call is made (and
> -        * thus the root bridge's pci_dev does not exist).
> -        */
> -       root->bus = pci_acpi_scan_root(root);
> -       if (!root->bus) {
> -               dev_err(&device->dev,
> -                       "Bus %04x:%02x not present in PCI namespace\n",
> -                       root->segment, (unsigned int)root->secondary.start);
> -               result = -ENODEV;
> -               goto end;
> -       }
> -
> -       /* Indicate support for various _OSC capabilities. */
>         if (pci_ext_cfg_avail())
>                 flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>         if (pcie_aspm_support_enabled()) {
> @@ -471,7 +451,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                 if (ACPI_FAILURE(status)) {
>                         dev_info(&device->dev, "ACPI _OSC support "
>                                 "notification failed, disabling PCIe ASPM\n");
> -                       pcie_no_aspm();
> +                       no_aspm = true;
>                         flags = base_flags;
>                 }
>         }
> @@ -503,7 +483,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                                  * We have ASPM control, but the FADT indicates
>                                  * that it's unsupported. Clear it.
>                                  */
> -                               pcie_clear_aspm(root->bus);
> +                               clear_aspm = true;
>                         }
>                 } else {
>                         dev_info(&device->dev,
> @@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                                 acpi_format_exception(status), flags);
>                         dev_info(&device->dev,
>                                  "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
> -                       pcie_no_aspm();
> +                       /*
> +                        * We want to disable aspm here, but aspm_disabled
> +                        * needs to remain in its state from boot so that we
> +                        * properly handle pcie 1.1 devices.  So we set this
> +                        * flag here, to defer the action until after the acpi
> +                        * root scan
> +                        */
> +                       no_aspm = true;
>                 }
>         } else {
>                 dev_info(&device->dev,
> @@ -520,6 +507,33 @@ static int acpi_pci_root_add(struct acpi_device *device,
>                          "(_OSC support mask: 0x%02x)\n", flags);
>         }
>
> +       /*
> +        * TBD: Need PCI interface for enumeration/configuration of roots.
> +        */
> +
> +       /*
> +        * Scan the Root Bridge
> +        * --------------------
> +        * Must do this prior to any attempt to bind the root device, as the
> +        * PCI namespace does not get created until this call is made (and
> +        * thus the root bridge's pci_dev does not exist).
> +        */
> +       root->bus = pci_acpi_scan_root(root);
> +       if (!root->bus) {
> +               dev_err(&device->dev,
> +                       "Bus %04x:%02x not present in PCI namespace\n",
> +                       root->segment, (unsigned int)root->secondary.start);
> +               result = -ENODEV;
> +               goto end;
> +       }
> +
> +       if (clear_aspm) {
> +               dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
> +               pcie_clear_aspm(root->bus);
> +       }
> +       if (no_aspm)
> +               pcie_no_aspm();
> +
>         pci_acpi_add_bus_pm_notifier(device, root->bus);
>         if (device->wakeup.flags.run_wake)
>                 device_set_run_wake(root->bus->bridge, true);

Also need to cc stable?

Acked-by: Yinghai Lu <yinghai@kernel.org>

Re: [PATCH v4] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Bjorn Helgaas]

On Thu, Aug 29, 2013 at 04:17:05PM -0400, Neil Horman wrote:
> This is a fix for:
> https://bugzilla.kernel.org/show_bug.cgi?id=60736
> 
> During the 3.8 devel cycle:
> 
> commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6
> Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
> Date:   Tue Oct 30 15:27:13 2012 +0900
> 
>     PCI/ACPI: Request _OSC control before scanning PCI root bus
> 
> went in to allow us to query the pcie hotplug flags during the acpi bus scan.
> It however caused problems with the disabling of pcie aspm, and so:
> commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> Author: Bjorn Helgaas <bhelgaas@google.com>
> Date:   Mon Apr 1 15:47:39 2013 -0600
> 
>     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
> 
> Backed it out.  This of course brought back the problem in which acpi took over
> hotplug ports that were meant to be controlled by pcie.
> 
> This patch gives us both items.  It lets us request _OSC control before scanning
> the pci root bus, but defers any disabling of aspm until after the scan is
> complete, allowing us to properly handle old pcie 1.1 devices aspm settings
> properly, as b8178f130e documents.
> 
> Tested successfully by myself.
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> CC: Len Brown <lenb@kernel.org>
> CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> CC: linux-acpi@vger.kernel.org
> CC: linux-pci@vger.kernel.org

I added Yinghai's ack and a stable tag and put this in pci/misc
for v3.12.  Thanks!

I reworked the changelog because I think the actual cause of the
regression was 3b63aaa70e, not the _OSC commits you mentioned:

8c33f51df4 ("PCI/ACPI: Request _OSC control before scanning PCI root bus")
appeared in v3.8 and broke ASPM but not acpiphp.

b8178f130e ('Revert "PCI/ACPI: Request _OSC control before scanning PCI
root bus"') appeared in v3.9 and fixed ASPM, leaving acpiphp working.

3b63aaa70e ("PCI: acpiphp: Do not use ACPI PCI subdriver mechanism")
appeared in v3.10, and I believe this is what actually broke acpiphp
because it moved the acpiphp initialization earlier, into the bus scan.

in v3.8:
    acpi_pci_root_add
      acpi_pci_osc_control_set          # request OS control
      pci_acpi_scan_root                # scan bus
    acpi_pci_root_start
      add_bridge                        # acpi_pci_driver .add method
        ...
          device_is_managed_by_native_pciehp	# OK

in v3.9:
    acpi_pci_root_add
      pci_acpi_scan_root                # scan bus
      acpi_pci_osc_control_set          # request OS control
      add_bridge                        # acpi_pci_driver .add method
        ...
          device_is_managed_by_native_pciehp	# OK

in v3.10:
    acpi_pci_root_add
      pci_acpi_scan_root                # scan bus
        ...
          acpiphp_enumerate_slots
            ...
              device_is_managed_by_native_pciehp	# PROBLEM
      acpi_pci_osc_control_set          # request OS control

So I added a stable tag for v3.10+ only.  I'll ask Linus to merge it
directly during the merge window for v3.12, and hopefully it will be
backported to the v3.10 and v3.11 stable trees soon after that.

Bjorn

> ---
>  drivers/acpi/pci_root.c | 62 ++++++++++++++++++++++++++++++-------------------
>  1 file changed, 38 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 5917839..6110fd2 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -378,6 +378,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	struct acpi_pci_root *root;
>  	u32 flags, base_flags;
>  	acpi_handle handle = device->handle;
> +	bool no_aspm = false, clear_aspm = false;
>  
>  	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
>  	if (!root)
> @@ -437,27 +438,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
>  	acpi_pci_osc_support(root, flags);
>  
> -	/*
> -	 * TBD: Need PCI interface for enumeration/configuration of roots.
> -	 */
> -
> -	/*
> -	 * Scan the Root Bridge
> -	 * --------------------
> -	 * Must do this prior to any attempt to bind the root device, as the
> -	 * PCI namespace does not get created until this call is made (and
> -	 * thus the root bridge's pci_dev does not exist).
> -	 */
> -	root->bus = pci_acpi_scan_root(root);
> -	if (!root->bus) {
> -		dev_err(&device->dev,
> -			"Bus %04x:%02x not present in PCI namespace\n",
> -			root->segment, (unsigned int)root->secondary.start);
> -		result = -ENODEV;
> -		goto end;
> -	}
> -
> -	/* Indicate support for various _OSC capabilities. */
>  	if (pci_ext_cfg_avail())
>  		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
>  	if (pcie_aspm_support_enabled()) {
> @@ -471,7 +451,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  		if (ACPI_FAILURE(status)) {
>  			dev_info(&device->dev, "ACPI _OSC support "
>  				"notification failed, disabling PCIe ASPM\n");
> -			pcie_no_aspm();
> +			no_aspm = true;
>  			flags = base_flags;
>  		}
>  	}
> @@ -503,7 +483,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  				 * We have ASPM control, but the FADT indicates
>  				 * that it's unsupported. Clear it.
>  				 */
> -				pcie_clear_aspm(root->bus);
> +				clear_aspm = true;
>  			}
>  		} else {
>  			dev_info(&device->dev,
> @@ -512,7 +492,14 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  				acpi_format_exception(status), flags);
>  			dev_info(&device->dev,
>  				 "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
> -			pcie_no_aspm();
> +			/*
> +			 * We want to disable aspm here, but aspm_disabled 
> +			 * needs to remain in its state from boot so that we
> +			 * properly handle pcie 1.1 devices.  So we set this
> +			 * flag here, to defer the action until after the acpi
> +			 * root scan
> +			 */
> +			no_aspm = true;
>  		}
>  	} else {
>  		dev_info(&device->dev,
> @@ -520,6 +507,33 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  			 "(_OSC support mask: 0x%02x)\n", flags);
>  	}
>  
> +	/*
> +	 * TBD: Need PCI interface for enumeration/configuration of roots.
> +	 */
> +
> +	/*
> +	 * Scan the Root Bridge
> +	 * --------------------
> +	 * Must do this prior to any attempt to bind the root device, as the
> +	 * PCI namespace does not get created until this call is made (and
> +	 * thus the root bridge's pci_dev does not exist).
> +	 */
> +	root->bus = pci_acpi_scan_root(root);
> +	if (!root->bus) {
> +		dev_err(&device->dev,
> +			"Bus %04x:%02x not present in PCI namespace\n",
> +			root->segment, (unsigned int)root->secondary.start);
> +		result = -ENODEV;
> +		goto end;
> +	}
> +
> +	if (clear_aspm) {
> +		dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
> +		pcie_clear_aspm(root->bus);
> +	}
> +	if (no_aspm)
> +		pcie_no_aspm();
> +
>  	pci_acpi_add_bus_pm_notifier(device, root->bus);
>  	if (device->wakeup.flags.run_wake)
>  		device_set_run_wake(root->bus->bridge, true);
> -- 
> 1.8.1.4
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH v4] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available

[Neil Horman]

On Thu, Aug 29, 2013 at 05:40:52PM -0600, Bjorn Helgaas wrote:
> On Thu, Aug 29, 2013 at 04:17:05PM -0400, Neil Horman wrote:
> > This is a fix for:
> > https://bugzilla.kernel.org/show_bug.cgi?id=60736
> > 
> > During the 3.8 devel cycle:
> > 
> > commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6
> > Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
> > Date:   Tue Oct 30 15:27:13 2012 +0900
> > 
> >     PCI/ACPI: Request _OSC control before scanning PCI root bus
> > 
> > went in to allow us to query the pcie hotplug flags during the acpi bus scan.
> > It however caused problems with the disabling of pcie aspm, and so:
> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e
> > Author: Bjorn Helgaas <bhelgaas@google.com>
> > Date:   Mon Apr 1 15:47:39 2013 -0600
> > 
> >     Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
> > 
> > Backed it out.  This of course brought back the problem in which acpi took over
> > hotplug ports that were meant to be controlled by pcie.
> > 
> > This patch gives us both items.  It lets us request _OSC control before scanning
> > the pci root bus, but defers any disabling of aspm until after the scan is
> > complete, allowing us to properly handle old pcie 1.1 devices aspm settings
> > properly, as b8178f130e documents.
> > 
> > Tested successfully by myself.
> > 
> > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > CC: Len Brown <lenb@kernel.org>
> > CC: "Rafael J. Wysocki" <rjw@sisk.pl>
> > CC: linux-acpi@vger.kernel.org
> > CC: linux-pci@vger.kernel.org
> 
> I added Yinghai's ack and a stable tag and put this in pci/misc
> for v3.12.  Thanks!
> 
> I reworked the changelog because I think the actual cause of the
> regression was 3b63aaa70e, not the _OSC commits you mentioned:
> 
> 8c33f51df4 ("PCI/ACPI: Request _OSC control before scanning PCI root bus")
> appeared in v3.8 and broke ASPM but not acpiphp.
> 
> b8178f130e ('Revert "PCI/ACPI: Request _OSC control before scanning PCI
> root bus"') appeared in v3.9 and fixed ASPM, leaving acpiphp working.
> 
> 3b63aaa70e ("PCI: acpiphp: Do not use ACPI PCI subdriver mechanism")
> appeared in v3.10, and I believe this is what actually broke acpiphp
> because it moved the acpiphp initialization earlier, into the bus scan.
> 
> in v3.8:
>     acpi_pci_root_add
>       acpi_pci_osc_control_set          # request OS control
>       pci_acpi_scan_root                # scan bus
>     acpi_pci_root_start
>       add_bridge                        # acpi_pci_driver .add method
>         ...
>           device_is_managed_by_native_pciehp	# OK
> 
> in v3.9:
>     acpi_pci_root_add
>       pci_acpi_scan_root                # scan bus
>       acpi_pci_osc_control_set          # request OS control
>       add_bridge                        # acpi_pci_driver .add method
>         ...
>           device_is_managed_by_native_pciehp	# OK
> 
> in v3.10:
>     acpi_pci_root_add
>       pci_acpi_scan_root                # scan bus
>         ...
>           acpiphp_enumerate_slots
>             ...
>               device_is_managed_by_native_pciehp	# PROBLEM
>       acpi_pci_osc_control_set          # request OS control
> 
> So I added a stable tag for v3.10+ only.  I'll ask Linus to merge it
> directly during the merge window for v3.12, and hopefully it will be
> backported to the v3.10 and v3.11 stable trees soon after that.
> 
> Bjorn
> 
Copy that, thanks!
Neil