Re: [PATCH v3 1/8] ACPI: fix synthetic HID for \_SB_

[ykzhao <yakui.zhao@intel.com>]

On Thu, 2009-09-24 at 11:36 +0800, Bjorn Helgaas wrote:
> On Thu, 2009-09-24 at 09:44 +0800, ykzhao wrote:
> > On Thu, 2009-09-24 at 00:19 +0800, Bjorn Helgaas wrote:
> > > On Tuesday 22 September 2009 08:21:46 pm ykzhao wrote:
> > > > On Tue, 2009-09-22 at 03:35 +0800, Bjorn Helgaas wrote:
> > > > > This makes \_SB_ show up as /sys/devices/LNXSYSTM:00/LNXSYBUS:00
> > > > > rather than "device:00".  This has been broken for a loooong time
> > > > > (at least since 2.6.13) because device->parent is an acpi_device
> > > > > pointer, not a handle.
> > > > 
> > > > > Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
> > > > > ---
> > > > >  drivers/acpi/scan.c |   18 ++++++------------
> > > > >  1 files changed, 6 insertions(+), 12 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> > > > > index 2c4cac5..e9227ea 100644
> > > > > --- a/drivers/acpi/scan.c
> > > > > +++ b/drivers/acpi/scan.c
> > > > > @@ -1100,6 +1100,12 @@ static void acpi_device_set_id(struct acpi_device *device)
> > > > >  		if (ACPI_IS_ROOT_DEVICE(device)) {
> > > > >  			hid = ACPI_SYSTEM_HID;
> > > > >  			break;
> > > > > +		} else if (ACPI_IS_ROOT_DEVICE(device->parent)) {
> > > 
> > > > Can we still add the judgement about the device type?
> > > >    device->type == ACPI_BUS_TYPE_DEVICE
> > > 
> > > We are already checking this because this test is inside the
> > > ACPI_BUS_TYPE_DEVICE case of a switch statement.
> > If this is checed inside the ACPI_BUS_TYPE_DEVICE case, can we delete
> > the following check as the type of root device is ACPI_BUS_TYPE_SYSTEM?
> >    If (ACPI_IS_ROOT_DEVICE(device)) {
> > 		hid = ACPI_SYSTEM_HID;
> > 		break;
> > 	}
> 
> What?  Are you saying that we shouldn't add a HID of "LNXSYSTM" to the
> root object?  I'm really not sure what you're proposing.
Maybe I mix the two patch sets. One has 8 patches. And another has 17
patches. In fact there exists the dependency between the two patch set.

And you delete the ACPI_BUS_TYPE_SYSTEM type in another patch set,
right?

What is the benefit if we change the type from ACPI_BUS_TYPE_SYSTEM to
ACPI_BUS_TYPE_DEVICE for the root device?

Thanks.
> 
> > > 
> > > > Where can I find the macro definition of ACPI_IS_ROOT_DEVICE?
> > > 
> > > It's patch 13/17 in the previous "ACPI: cleanups for hotplug" series.
> > > I should have mentioned that this series depends on that one.
> > Yes. 
> > I also find that it is defined in patch 13/17.
> > It had better be defined as early as possible. Otherwise we may fail in
> > git-bisect.
> 
> Absolutely.  I'm pretty sure I defined ACPI_IS_ROOT_DEVICE before any
> uses of it, but please point it out if I'm mistaken.
> 
> Bjorn
> 
> > > > > +			/* \_SB_, the only root-level namespace device */
> > > > > +			hid = ACPI_BUS_HID;
> > > > > +			strcpy(device->pnp.device_name, ACPI_BUS_DEVICE_NAME);
> > > > > +			strcpy(device->pnp.device_class, ACPI_BUS_CLASS);
> > > > > +			break;
> > > > >  		}
> > > > >  
> > > > >  		status = acpi_get_object_info(device->handle, &info);
> > > > > @@ -1149,18 +1155,6 @@ static void acpi_device_set_id(struct acpi_device *device)
> > > > >  		break;
> > > > >  	}
> > > > >  
> > > > > -	/*
> > > > > -	 * \_SB
> > > > > -	 * ----
> > > > > -	 * Fix for the system root bus device -- the only root-level device.
> > > > > -	 */
> > > > > -	if (((acpi_handle)device->parent == ACPI_ROOT_OBJECT) &&
> > > > > -	     (device->device_type == ACPI_BUS_TYPE_DEVICE)) {
> > > > > -		hid = ACPI_BUS_HID;
> > > > > -		strcpy(device->pnp.device_name, ACPI_BUS_DEVICE_NAME);
> > > > > -		strcpy(device->pnp.device_class, ACPI_BUS_CLASS);
> > > > > -	}
> > > > > -
> > > > >  	if (hid) {
> > > > >  		device->pnp.hardware_id = ACPI_ALLOCATE_ZEROED(strlen (hid) + 1);
> > > > >  		if (device->pnp.hardware_id) {
> > > > > 
> > > > > --
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> > > > 
> > > > 
> > > 
> > > 
> > 
> 

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