On Sat, Aug 04, 2018 at 12:14:00PM +0200, Christoph Hellwig wrote:
> There is currently no way for a PCIe bridge to impose constraints on
> devices added to it. For example, the Xilinx PCIe host bridge only
> supports 32-bit physical addresses (due to a limitation on the AXI
> port's address width). Thus, even devices that claim to support 64-bit
> DMA addresses must be restricted to 32-bit addresses when attached to
> this host controller.
>
> This patch adds a "add_device" method to struct pci_host_bridge that
> allows the host driver to act upon acting adding devices.
>
> Based on an earlier patch from Wesley W. Terpstra <wesley@xxxxxxxxxx>.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> drivers/pci/probe.c | 6 ++++++
> include/linux/pci.h | 1 +
> 2 files changed, 7 insertions(+)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index ac876e32de4b..452190fb05e7 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2290,6 +2290,7 @@ static void pci_set_msi_domain(struct pci_dev *dev)
>
> void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
> {
> + struct pci_host_bridge *host = pci_find_host_bridge(bus);
> int ret;
>
> pci_configure_device(dev);
> @@ -2328,6 +2329,11 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
> ret = pcibios_add_device(dev);
> WARN_ON(ret < 0);
>
> + if (host->add_device) {
> + ret = host->add_device(dev);
> + WARN_ON(ret < 0);
> + }
This looks fine; we could go a step further and make the hunk above
the default (weak) implementation of pcibios_add_device() that is
currently a NOP returning 0, I will remove it for v4.20.
I am fine with the patch as-is (even though I am not a big fan of
those WARN_ON but that's not a problem related to your patch, as you
said we are *not* handling the ret value in the current mainline).
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> +
> /* Set up MSI IRQ domain */
> pci_set_msi_domain(dev);
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index abd5d5e17aee..1524adbb30ab 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -485,6 +485,7 @@ struct pci_host_bridge {
> resource_size_t start,
> resource_size_t size,
> resource_size_t align);
> + int (*add_device)(struct pci_dev *dev);
> unsigned long private[0] ____cacheline_aligned;
> };
>
> --
> 2.18.0
>
