Re: [PATCH V3 11/21] pci, acpi: Move ACPI host bridge device companion assignment to core code.

[Tomasz Nowicki]

On 19.01.2016 17:02, Lorenzo Pieralisi wrote:
> On Wed, Jan 13, 2016 at 02:20:57PM +0100, Tomasz Nowicki wrote:
[...]
> > device via pci_create_root_bus parameter (as the ACPI device type)
>
> I do not understand what you mean by "as the ACPI device type".

See below.

> > and using ACPI_COMPANION_SET in core code for ACPI boot method.
> > ACPI_COMPANION_SET is safe to run for all cases DT, ACPI and DT&ACPI.
> >
> > Suggested-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > Signed-off-by: Tomasz Nowicki <tn@xxxxxxxxxxxx>
> > ---
> >   drivers/acpi/pci_root.c | 5 ++++-
> >   drivers/pci/probe.c     | 2 ++
> >   2 files changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > index ae3fe4e..a65c8c2 100644
> > --- a/drivers/acpi/pci_root.c
> > +++ b/drivers/acpi/pci_root.c
> > @@ -846,7 +846,10 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
> >
> >   	pci_acpi_root_add_resources(info);
> >   	pci_add_resource(&info->resources, &root->secondary);
> > -	bus = pci_create_root_bus(NULL, busnum, ops->pci_ops,
> > +
> > +	/* Root bridge device needs to be sure of parent ACPI type */
> > +	ACPI_COMPANION_SET(&device->dev, device);
>
> I do not understand why the code above is needed, can you elaborate
> please ?

This makes sure that device->dev can be identified as ACPI device, so we 
can use to_acpi_device_node() and assign companion safely below.

> > +	bus = pci_create_root_bus(&device->dev, busnum, ops->pci_ops,
> >   				  sysdata, &info->resources);
> >   	if (!bus)
> >   		goto out_release_info;
> > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > index 553a029..cad836f 100644
> > --- a/drivers/pci/probe.c
> > +++ b/drivers/pci/probe.c
> > @@ -2107,6 +2107,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> >   	bridge->dev.parent = parent;
> >   	bridge->dev.release = pci_release_host_bridge_dev;
> >   	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
> > +	ACPI_COMPANION_SET(&bridge->dev,
> > +			   parent ? to_acpi_device_node(parent->fwnode) : NULL);

pci_create_root_bus() can be called with DT device, then 
ACPI_COMPANION_SET assign no companion to bridge device.

Thanks,
Tomasz