On Wed, May 28, 2014 at 01:14:53PM -0400, Murali Karicheri wrote:
> Call pcie_bus_configure_settings on ARM, like for other platforms.
> pcie_bus_configure_settings makes sure the MPS across the bus is
> uniform and provides the ability to tune the MRSS and MPS to higher
> performance values. This is particularly important for embedded where
> there is no firmware to program these PCI-E settings for the OS.
>
> Signed-off-by: Murali Karicheri <m-karicheri2@xxxxxx>
>
> CC: Russell King <linux@xxxxxxxxxxxxxxxx>
> CC: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> CC: Arnd Bergmann <arnd@xxxxxxxx>
> CC: Jason Gunthorpe <jgunthorpe@xxxxxxxxxxxxxxxxxxxx>
> CC: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> ---
> - Fixed comments against initial version
> arch/arm/kernel/bios32.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> index 16d43cd..17a26c1 100644
> --- a/arch/arm/kernel/bios32.c
> +++ b/arch/arm/kernel/bios32.c
> @@ -545,6 +545,18 @@ void pci_common_init_dev(struct device *parent, struct hw_pci *hw)
> */
> pci_bus_add_devices(bus);
> }
> +
> + list_for_each_entry(sys, &head, node) {
> + struct pci_bus *bus = sys->bus;
> +
> + /* Configure PCI Express settings */
> + if (bus && !pci_has_flag(PCI_PROBE_ONLY)) {
> + struct pci_bus *child;
> +
> + list_for_each_entry(child, &bus->children, node)
> + pcie_bus_configure_settings(child);
This patch (8b5742ad156d ("ARM/PCI: Call pcie_bus_configure_settings() to
set MPS")) has been upstream since v3.16-rc1, but I think we goofed.
The MPS configuration should be done *before* pci_bus_add_devices(). After
pci_bus_add_devices(), drivers may be bound to devices, and the PCI core
shouldn't touch device configuration while a driver owns the device.
Looking at the code, it seems like it would have been simpler to do this in
the existing loop:
list_for_each_entry(sys, &head, node) {
struct pci_bus *bus = sys->bus;
if (bus && !pci_has_flag(PCI_PROBE_ONLY)) {
pci_bus_size_bridges(bus);
pci_bus_assign_resources(bus);
list_for_each_entry(child, &bus->children, node)
pcie_bus_configure_settings(child);
}
pci_bus_add_devices(bus);
}
so maybe there's some reason I'm not aware of for not doing it that way?
> + }
> + }
> }
>
> #ifndef CONFIG_PCI_HOST_ITE8152
> --
> 1.7.9.5
>
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