On Sun, 2011-10-02 at 22:17 -0500, Jon Mason wrote:
> On Sun, Oct 2, 2011 at 12:32 AM, Benjamin Herrenschmidt
> <benh@xxxxxxxxxxxxxxxxxxx> wrote:
> > 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 ?
>
> I don't believe there is an existing pcie boot arg parameter logic,
> and it seems overkill to add one just for this.
>
> If you don't have any other issues with this, I'd like to send this
> and the backlog to Linus.
Ok.
> Thanks,
> Jon
>
> >
> > 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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