On Sat, 2011-10-01 at 12:36 -0500, Jon Mason wrote:
> Add the ability to disable PCI-E MPS turning and using the BIOS
> configured MPS defaults. Due to the number of issues recently
> discovered on some x86 chipsets, make this the default behavior.
>
> Also, add the option for peer to peer DMA MPS configuration. Peer to
> peer DMA is outside the scope of this patch, but MPS configuration could
> prevent it from working by having the MPS on one root port different
> than the MPS on another. To work around this, simply make the system
> wide MPS the smallest possible value (128B).
Should this be instead pcie=xxx ?
Cheers,
Ben.
> Signed-off-by: Jon Mason <mason@xxxxxxxx>
> ---
> drivers/pci/pci.c | 6 +++++-
> drivers/pci/probe.c | 14 +++++++++++++-
> include/linux/pci.h | 3 ++-
> 3 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index d369316..5db5986 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -77,7 +77,7 @@ unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE;
> unsigned long pci_hotplug_io_size = DEFAULT_HOTPLUG_IO_SIZE;
> unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE;
>
> -enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_SAFE;
> +enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_TUNE_OFF;
>
> /*
> * The default CLS is used if arch didn't set CLS explicitly and not
> @@ -3582,10 +3582,14 @@ static int __init pci_setup(char *str)
> pci_hotplug_io_size = memparse(str + 9, &str);
> } else if (!strncmp(str, "hpmemsize=", 10)) {
> pci_hotplug_mem_size = memparse(str + 10, &str);
> + } else if (!strncmp(str, "pcie_bus_tune_off", 17)) {
> + pcie_bus_config = PCIE_BUS_TUNE_OFF;
> } else if (!strncmp(str, "pcie_bus_safe", 13)) {
> pcie_bus_config = PCIE_BUS_SAFE;
> } else if (!strncmp(str, "pcie_bus_perf", 13)) {
> pcie_bus_config = PCIE_BUS_PERFORMANCE;
> + } else if (!strncmp(str, "pcie_bus_peer2peer", 18)) {
> + pcie_bus_config = PCIE_BUS_PEER2PEER;
> } else {
> printk(KERN_ERR "PCI: Unknown option `%s'\n",
> str);
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index a919db2..4829424 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1451,12 +1451,24 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data)
> */
> void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
> {
> - u8 smpss = mpss;
> + u8 smpss;
>
> if (!pci_is_pcie(bus->self))
> return;
>
> + if (pcie_bus_config == PCIE_BUS_TUNE_OFF)
> + return;
> +
> + /* FIXME - Peer to peer DMA is possible, though the endpoint would need
> + * to be aware to the MPS of the destination. To work around this,
> + * simply force the MPS of the entire system to the smallest possible.
> + */
> + if (pcie_bus_config == PCIE_BUS_PEER2PEER)
> + smpss = 0;
> +
> if (pcie_bus_config == PCIE_BUS_SAFE) {
> + smpss = mpss;
> +
> pcie_find_smpss(bus->self, &smpss);
> pci_walk_bus(bus, pcie_find_smpss, &smpss);
> }
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 8c230cb..9fc0122 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -621,8 +621,9 @@ struct pci_driver {
> extern void pcie_bus_configure_settings(struct pci_bus *bus, u8 smpss);
>
> enum pcie_bus_config_types {
> - PCIE_BUS_PERFORMANCE,
> + PCIE_BUS_TUNE_OFF,
> PCIE_BUS_SAFE,
> + PCIE_BUS_PERFORMANCE,
> PCIE_BUS_PEER2PEER,
> };
>
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