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

From: Alex Williamson
Date: Wed Oct 30 2013 - 09:57:58 EST


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@xxxxxxxxxxxxxxx>
> ---
> 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);



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