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

[Lorenzo Pieralisi]

On Wed, Jan 13, 2016 at 02:20:57PM +0100, Tomasz Nowicki wrote:
> Currently we have two platforms (x86 & ia64) capable of PCI ACPI host
> bridge initialization. They both use sysdata pill to pass down parent

pill ?

> device reference and both relay on NULL parent in pci_create_root_bus()

s/relay/rely

> to validate sysdata content.
> 
> It looks hacky and prevent us from getting some frimware specific

"prevents us from getting some firmware..."

> info for PCI host controller e.g. bus domain number.
> However, it seems we can overcome that blocker by passing down parent

It does not seem, either this patch overcomes the issue and it is
accepted, or it does not and it is discarded.

> 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".

> 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 ?

Thanks,
Lorenzo

> +	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);
>  	error = pcibios_root_bridge_prepare(bridge);
>  	if (error) {
>  		kfree(bridge);
> -- 
> 1.9.1
>