Re: [PATCH v5 7/9] PCI: xgene: Set msi_controller->dev to platform_device, not pci_bus

[Bjorn Helgaas <bhelgaas@google.com>]

On Tue, Aug 04, 2015 at 04:54:42PM -0500, Bjorn Helgaas wrote:
> Other users of struct msi_controller set msi->dev to the platform_device of
> the PCI host controller, not the device of the pci_bus for the root bus.
> 
> Set X-Gene's msi_controller->dev to the PCI host controller platform_device
> as other platforms do.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/host/pci-xgene.c |    7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-xgene.c b/drivers/pci/host/pci-xgene.c
> index 4c2fb1f..5e0d6de 100644
> --- a/drivers/pci/host/pci-xgene.c
> +++ b/drivers/pci/host/pci-xgene.c
> @@ -501,7 +501,8 @@ static int xgene_pcie_setup(struct xgene_pcie_port *port,
>  	return 0;
>  }
>  
> -static int xgene_pcie_msi_enable(struct pci_bus *bus)
> +static int xgene_pcie_msi_enable(struct xgene_pcie_port *port,
> +				 struct pci_bus *bus)
>  {
>  	struct device_node *msi_node;
>  
> @@ -515,7 +516,7 @@ static int xgene_pcie_msi_enable(struct pci_bus *bus)
>  		return -ENODEV;
>  
>  	of_node_put(msi_node);
> -	bus->msi->dev = &bus->dev;
> +	bus->msi->dev = &port->dev;

Thomas, the surrounding code here and in mvebu_pcie_msi_enable() looks like
this:

  pcie->msi = of_pci_find_msi_chip_by_node(msi_node);
  pcie->msi->dev = &pcie->pdev->dev;

It seems sort of strange to search for a struct msi_controller, then set
the "dev" field inside it.  This code isn't really the owner of the
msi_controller, and it seems like in principle at least, the
of_pci_find_msi_chip_by_node() interface could be used by several clients.
Then it's not clear which one of them should update msi->dev.

It would make more sense to me if the caller of of_pci_msi_chip_add() set
the msi->dev field.  But I don't know whether that's feasible.  I don't
even know what msi->dev is used for.

Bjorn