[PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Mika Westerberg]

Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
notifies) changed the enable_slot() to check return value of pci_scan_slot()
and if it is zero return early from the function. It means that there were
no new devices in this particular slot.

However, if a device appeared deeper in the hierarchy the code now ignores
it causing things like Thunderbolt chaining fail to recognize new devices.

The problem with Alex Williamson's machine was solved with commit
a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
checks) and hence we should be able to restore the original functionality
that we always rescan on bus check notification.

On a device check notification we still check what acpiphp_rescan_slot()
returns and on zero bail out early.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
Alex,

Are you able to check if your machine still works and doesn't slow down
during boot after this patch is applied?

Thanks.

 drivers/pci/hotplug/acpiphp_glue.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index be12fbf..1ea7523 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -552,9 +552,8 @@ static void __ref enable_slot(struct acpiphp_slot *slot)
 	struct acpiphp_func *func;
 	int max, pass;
 	LIST_HEAD(add_list);
-	int nr_found;
 
-	nr_found = acpiphp_rescan_slot(slot);
+	acpiphp_rescan_slot(slot);
 	max = acpiphp_max_busnr(bus);
 	for (pass = 0; pass < 2; pass++) {
 		list_for_each_entry(dev, &bus->devices, bus_list) {
@@ -574,9 +573,6 @@ static void __ref enable_slot(struct acpiphp_slot *slot)
 		}
 	}
 	__pci_bus_assign_resources(bus, &add_list, NULL);
-	/* Nothing more to do here if there are no new devices on this bus. */
-	if (!nr_found && (slot->flags & SLOT_ENABLED))
-		return;
 
 	acpiphp_sanitize_bus(bus);
 	acpiphp_set_hpp_values(bus);
-- 
1.8.4.rc3

Re: [PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Rafael J. Wysocki]

On Wednesday, October 30, 2013 02:40:36 PM Mika Westerberg wrote:
> Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
> notifies) changed the enable_slot() to check return value of pci_scan_slot()
> and if it is zero return early from the function. It means that there were
> no new devices in this particular slot.
> 
> However, if a device appeared deeper in the hierarchy the code now ignores
> it causing things like Thunderbolt chaining fail to recognize new devices.
> 
> The problem with Alex Williamson's machine was solved with commit
> a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
> checks) and hence we should be able to restore the original functionality
> that we always rescan on bus check notification.
> 
> On a device check notification we still check what acpiphp_rescan_slot()
> returns and on zero bail out early.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

So, this is a revert of commit a47d8c8, correct?

Rafael


> ---
> Alex,
> 
> Are you able to check if your machine still works and doesn't slow down
> during boot after this patch is applied?
> 
> Thanks.
> 
>  drivers/pci/hotplug/acpiphp_glue.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index be12fbf..1ea7523 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -552,9 +552,8 @@ static void __ref enable_slot(struct acpiphp_slot *slot)
>  	struct acpiphp_func *func;
>  	int max, pass;
>  	LIST_HEAD(add_list);
> -	int nr_found;
>  
> -	nr_found = acpiphp_rescan_slot(slot);
> +	acpiphp_rescan_slot(slot);
>  	max = acpiphp_max_busnr(bus);
>  	for (pass = 0; pass < 2; pass++) {
>  		list_for_each_entry(dev, &bus->devices, bus_list) {
> @@ -574,9 +573,6 @@ static void __ref enable_slot(struct acpiphp_slot *slot)
>  		}
>  	}
>  	__pci_bus_assign_resources(bus, &add_list, NULL);
> -	/* Nothing more to do here if there are no new devices on this bus. */
> -	if (!nr_found && (slot->flags & SLOT_ENABLED))
> -		return;
>  
>  	acpiphp_sanitize_bus(bus);
>  	acpiphp_set_hpp_values(bus);
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Mika Westerberg]

On Wed, Oct 30, 2013 at 02:01:40PM +0100, Rafael J. Wysocki wrote:
> On Wednesday, October 30, 2013 02:40:36 PM Mika Westerberg wrote:
> > Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
> > notifies) changed the enable_slot() to check return value of pci_scan_slot()
> > and if it is zero return early from the function. It means that there were
> > no new devices in this particular slot.
> > 
> > However, if a device appeared deeper in the hierarchy the code now ignores
> > it causing things like Thunderbolt chaining fail to recognize new devices.
> > 
> > The problem with Alex Williamson's machine was solved with commit
> > a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
> > checks) and hence we should be able to restore the original functionality
> > that we always rescan on bus check notification.
> > 
> > On a device check notification we still check what acpiphp_rescan_slot()
> > returns and on zero bail out early.
> > 
> > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> 
> So, this is a revert of commit a47d8c8, correct?

Correct.

Plain revert didn't work because the code has changed after that commit.

Re: [PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Rafael J. Wysocki]

On Wednesday, October 30, 2013 03:04:16 PM Mika Westerberg wrote:
> On Wed, Oct 30, 2013 at 02:01:40PM +0100, Rafael J. Wysocki wrote:
> > On Wednesday, October 30, 2013 02:40:36 PM Mika Westerberg wrote:
> > > Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
> > > notifies) changed the enable_slot() to check return value of pci_scan_slot()
> > > and if it is zero return early from the function. It means that there were
> > > no new devices in this particular slot.
> > > 
> > > However, if a device appeared deeper in the hierarchy the code now ignores
> > > it causing things like Thunderbolt chaining fail to recognize new devices.
> > > 
> > > The problem with Alex Williamson's machine was solved with commit
> > > a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
> > > checks) and hence we should be able to restore the original functionality
> > > that we always rescan on bus check notification.
> > > 
> > > On a device check notification we still check what acpiphp_rescan_slot()
> > > returns and on zero bail out early.
> > > 
> > > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > 
> > So, this is a revert of commit a47d8c8, correct?
> 
> Correct.
> 
> Plain revert didn't work because the code has changed after that commit.

Yeah.

Well, it would be good to know if it affects the Alex' system, but anyway
I added it to the 3.13 queue for now.  We may be able to get it into 3.12
if Alex confirms that it works for him shortly, but if that doesn't happen
we can just ask stable to pick it up later.

Thanks!

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

Re: [PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Alex Williamson]

On Wed, 2013-10-30 at 14:40 +0200, Mika Westerberg wrote:
> Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
> notifies) changed the enable_slot() to check return value of pci_scan_slot()
> and if it is zero return early from the function. It means that there were
> no new devices in this particular slot.
> 
> However, if a device appeared deeper in the hierarchy the code now ignores
> it causing things like Thunderbolt chaining fail to recognize new devices.
> 
> The problem with Alex Williamson's machine was solved with commit
> a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
> checks) and hence we should be able to restore the original functionality
> that we always rescan on bus check notification.
> 
> On a device check notification we still check what acpiphp_rescan_slot()
> returns and on zero bail out early.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
> Alex,
> 
> Are you able to check if your machine still works and doesn't slow down
> during boot after this patch is applied?

Looks ok to me, no new console output or boot delay.  Thanks,

Alex

>  drivers/pci/hotplug/acpiphp_glue.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index be12fbf..1ea7523 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -552,9 +552,8 @@ static void __ref enable_slot(struct acpiphp_slot *slot)
>  	struct acpiphp_func *func;
>  	int max, pass;
>  	LIST_HEAD(add_list);
> -	int nr_found;
>  
> -	nr_found = acpiphp_rescan_slot(slot);
> +	acpiphp_rescan_slot(slot);
>  	max = acpiphp_max_busnr(bus);
>  	for (pass = 0; pass < 2; pass++) {
>  		list_for_each_entry(dev, &bus->devices, bus_list) {
> @@ -574,9 +573,6 @@ static void __ref enable_slot(struct acpiphp_slot *slot)
>  		}
>  	}
>  	__pci_bus_assign_resources(bus, &add_list, NULL);
> -	/* Nothing more to do here if there are no new devices on this bus. */
> -	if (!nr_found && (slot->flags & SLOT_ENABLED))
> -		return;
>  
>  	acpiphp_sanitize_bus(bus);
>  	acpiphp_set_hpp_values(bus);

Re: [PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Mika Westerberg]

On Wed, Oct 30, 2013 at 07:57:46AM -0600, Alex Williamson wrote:
> On Wed, 2013-10-30 at 14:40 +0200, Mika Westerberg wrote:
> > Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
> > notifies) changed the enable_slot() to check return value of pci_scan_slot()
> > and if it is zero return early from the function. It means that there were
> > no new devices in this particular slot.
> > 
> > However, if a device appeared deeper in the hierarchy the code now ignores
> > it causing things like Thunderbolt chaining fail to recognize new devices.
> > 
> > The problem with Alex Williamson's machine was solved with commit
> > a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
> > checks) and hence we should be able to restore the original functionality
> > that we always rescan on bus check notification.
> > 
> > On a device check notification we still check what acpiphp_rescan_slot()
> > returns and on zero bail out early.
> > 
> > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > ---
> > Alex,
> > 
> > Are you able to check if your machine still works and doesn't slow down
> > during boot after this patch is applied?
> 
> Looks ok to me, no new console output or boot delay.  Thanks,

Thanks!

Re: [PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Rafael J. Wysocki]

On Wednesday, October 30, 2013 07:57:46 AM Alex Williamson wrote:
> On Wed, 2013-10-30 at 14:40 +0200, Mika Westerberg wrote:
> > Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
> > notifies) changed the enable_slot() to check return value of pci_scan_slot()
> > and if it is zero return early from the function. It means that there were
> > no new devices in this particular slot.
> > 
> > However, if a device appeared deeper in the hierarchy the code now ignores
> > it causing things like Thunderbolt chaining fail to recognize new devices.
> > 
> > The problem with Alex Williamson's machine was solved with commit
> > a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
> > checks) and hence we should be able to restore the original functionality
> > that we always rescan on bus check notification.
> > 
> > On a device check notification we still check what acpiphp_rescan_slot()
> > returns and on zero bail out early.
> > 
> > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > ---
> > Alex,
> > 
> > Are you able to check if your machine still works and doesn't slow down
> > during boot after this patch is applied?
> 
> Looks ok to me, no new console output or boot delay.  Thanks,

Great, thanks!

May I add your Tested-by to it, then?

Rafael

Re: [PATCH] ACPI / hotplug / PCI: Always rescan the slot for new devices

[Alex Williamson]

On Wed, 2013-10-30 at 15:13 +0100, Rafael J. Wysocki wrote:
> On Wednesday, October 30, 2013 07:57:46 AM Alex Williamson wrote:
> > On Wed, 2013-10-30 at 14:40 +0200, Mika Westerberg wrote:
> > > Commit 2dc4128 (ACPI / hotplug / PCI: Avoid doing too much for spurious
> > > notifies) changed the enable_slot() to check return value of pci_scan_slot()
> > > and if it is zero return early from the function. It means that there were
> > > no new devices in this particular slot.
> > > 
> > > However, if a device appeared deeper in the hierarchy the code now ignores
> > > it causing things like Thunderbolt chaining fail to recognize new devices.
> > > 
> > > The problem with Alex Williamson's machine was solved with commit
> > > a47d8c8 (ACPI / hotplug / PCI: Avoid parent bus rescans on spurious device
> > > checks) and hence we should be able to restore the original functionality
> > > that we always rescan on bus check notification.
> > > 
> > > On a device check notification we still check what acpiphp_rescan_slot()
> > > returns and on zero bail out early.
> > > 
> > > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > > ---
> > > Alex,
> > > 
> > > Are you able to check if your machine still works and doesn't slow down
> > > during boot after this patch is applied?
> > 
> > Looks ok to me, no new console output or boot delay.  Thanks,
> 
> Great, thanks!
> 
> May I add your Tested-by to it, then?

Sure

Tested-by: Alex Williamson <alex.williamson@redhat.com>