[PATCH] PCI: Include PCI-to-PCIe bridges as "Downstream Ports"

[PATCH] PCI: Include PCI-to-PCIe bridges as "Downstream Ports"

[Bjorn Helgaas]

A PCI/PCI-X to PCI Express bridge, sometimes referred to as a "reverse
bridge", is a bridge with conventional PCI or PCI-X on its primary side and
a PCI Express Port on its secondary (downstream) side.

That PCIe Port is a Downstream Port and could be connected to a slot, just
like a Root Port or a Switch Downstream Port.  Make pcie_downstream_port()
return true for them, so we can access the Slot registers in the PCIe
capability.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 1c8051003e67..9b09cd31158c 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -700,7 +700,8 @@ static bool pcie_downstream_port(const struct pci_dev *dev)
 	int type = pci_pcie_type(dev);
 
 	return type == PCI_EXP_TYPE_ROOT_PORT ||
-	       type == PCI_EXP_TYPE_DOWNSTREAM;
+	       type == PCI_EXP_TYPE_DOWNSTREAM ||
+	       type == PCI_EXP_TYPE_PCIE_BRIDGE;
 }
 
 bool pcie_cap_has_lnkctl(const struct pci_dev *dev)

Re: [PATCH] PCI: Include PCI-to-PCIe bridges as "Downstream Ports"

[Bjorn Helgaas]

On Wed, Apr 19, 2017 at 08:53:32AM -0500, Bjorn Helgaas wrote:
> A PCI/PCI-X to PCI Express bridge, sometimes referred to as a "reverse
> bridge", is a bridge with conventional PCI or PCI-X on its primary side and
> a PCI Express Port on its secondary (downstream) side.
> 
> That PCIe Port is a Downstream Port and could be connected to a slot, just
> like a Root Port or a Switch Downstream Port.  Make pcie_downstream_port()
> return true for them, so we can access the Slot registers in the PCIe
> capability.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

I applied this to pci/enumeration for v4.12.

> diff --git a/drivers/pci/access.c b/drivers/pci/access.c
> index 1c8051003e67..9b09cd31158c 100644
> --- a/drivers/pci/access.c
> +++ b/drivers/pci/access.c
> @@ -700,7 +700,8 @@ static bool pcie_downstream_port(const struct pci_dev *dev)
>  	int type = pci_pcie_type(dev);
>  
>  	return type == PCI_EXP_TYPE_ROOT_PORT ||
> -	       type == PCI_EXP_TYPE_DOWNSTREAM;
> +	       type == PCI_EXP_TYPE_DOWNSTREAM ||
> +	       type == PCI_EXP_TYPE_PCIE_BRIDGE;
>  }
>  
>  bool pcie_cap_has_lnkctl(const struct pci_dev *dev)