Re: [PATCH 2/3] Do not use acpi_device to find pci root bridge in_init code.

[Tang Chen]

On 10/12/2012 06:36 PM, Jiang Liu wrote:
> On 2012-10-12 18:31, Tang Chen wrote:
> > When the kernel is being initialized, and some hardwares are not added
> > to system, there won't be acpi_device structs for these devices. But
> > acpi_is_root_bridge() depends on acpi_device struct. As a result, all
> > the not-added root bridge will not be judged as a root bridge in
> > find_root_bridges(). And further more, no handle_hotplug_event_root()
> > notifier will be installed for them.
> >
> > This patch introduces a new api to find all root bridges in system by
> > getting HID directly from ACPI namespace, not depending on acpi_device
> > struct.
> >
> > Signed-off-by: Tang Chen<tangchen@xxxxxxxxxxxxxx>
> > ---
> >   drivers/acpi/pci_root.c |   27 ++++++++++++++++++++++-----
> >   1 files changed, 22 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > index 7d0fb03..3819bee 100644
> > --- a/drivers/acpi/pci_root.c
> > +++ b/drivers/acpi/pci_root.c
> > @@ -128,9 +128,6 @@ EXPORT_SYMBOL_GPL(acpi_get_pci_rootbridge_handle);
> >   /**
> >    * acpi_is_root_bridge - determine whether an ACPI CA node is a PCI root bridge
> >    * @handle - the ACPI CA node in question.
> > - *
> > - * Note: we could make this API take a struct acpi_device * instead, but
> > - * for now, it's more convenient to operate on an acpi_handle.
> >    */
> >   int acpi_is_root_bridge(acpi_handle handle)
> >   {
> > @@ -138,8 +135,28 @@ int acpi_is_root_bridge(acpi_handle handle)
> >   	struct acpi_device *device;
> >
> >   	ret = acpi_bus_get_device(handle,&device);
> > -	if (ret)
> > -		return 0;
> > +	if (ret) {
> > +		/**
> > +		 * If a device is not added to the system yet, there won't be
> > +		 * an acpi_device struct for it. But it doesn't mean it is not
> > +		 * a PCI root bridge. In this case we need to get HID and CID
> > +		 * from ACPI namespace directly.
> > +		 */
> > +		struct acpi_device_info *info;
> > +		acpi_status status;
> > +		status = acpi_get_object_info(handle,&info);
> > +		if (ACPI_FAILURE(status)) {
> > +			printk(KERN_ERR PREFIX "%s: Error reading"
> > +					       "device info\n", __func__);
> > +			return 0;
> > +		}
> > +
> > +		ret = acpi_match_object_info_ids(info, root_device_ids);
> > +		if (ret)
> > +			return 0;
> > +		else
> > +			return 1;
> > +	}
> I have sent a similar patch to Yinghai before. For simplicity, we could
> use acpi_match_object_info_ids() instead of acpi_match_device_ids()
> directly.

Hum, I must have missed it. :)
Using acpi_match_object_info_ids() directly seems good. I'm just worry
about if it could cause any other problem. :)

So now, is this bug fixed ? And we don't need these patches, right ?

Thanks. :)

> Thanks!
> Gerry
>
> >   	ret = acpi_match_device_ids(device, root_device_ids);
> >   	if (ret)
>
>
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