Hi Jon, Thanks for your review and comments! On 2013/8/15 0:59, Jon Mason wrote: > On Wed, Aug 14, 2013 at 2:01 AM, Yijing Wang <wangyijing@xxxxxxxxxx> wrote: >> Currently we don't update device's mps vaule when doing > > Spelling nit, "value" Will update, thanks! > >> pci device hot-add. The hot-added device's mps will be set >> to default value (128B). But the upstream port device's mps >> may be larger than 128B which was set by firmware during >> system bootup. In this case the new added device may not >> work normally. This patch try to update the hot added device >> mps euqal to its parent mps, if device mpss < parent mps, > > Spelling nit, "equal". Will update. > >> print warning. >> >> References: https://bugzilla.kernel.org/show_bug.cgi?id=60671 >> Reported-by: Yijing Wang <wangyijing@xxxxxxxxxx> >> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx> >> Cc: Jon Mason <jdmason@xxxxxxxx> >> Cc: stable@xxxxxxxxxxxxxxx # 3.4+ >> --- >> drivers/pci/probe.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- >> 1 files changed, 49 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c >> index 0699ec0..0d47b4a 100644 >> --- a/drivers/pci/probe.c >> +++ b/drivers/pci/probe.c >> @@ -1621,6 +1621,45 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data) >> return 0; >> } >> >> +static int pcie_bus_update_set(struct pci_dev *dev, void *data) >> +{ >> + int mps, p_mps, mpss; >> + struct pci_dev *parent; >> + >> + if (!pci_is_pcie(dev) || !dev->bus->self) >> + return 0; >> + >> + parent = dev->bus->self; >> + mps = pcie_get_mps(dev); >> + p_mps = pcie_get_mps(dev->bus->self); >> + >> + if (mps >= p_mps) > > I'm probably overly paranoid, but I worry what would happen in the > > case. Should we try and force the device MPS to a sane value or are > we confident that this will never happen? In the original patch, this patch will update the mps if mps != p_mps. For conservative, this patch only to fix the issue occurs in hot-plug(mps will never larger than p_mps). I don't know whether BIOS will set mps like mps > p_mps for certain purposes.:) > >> + return 0; >> + >> + /* we only update the device mps, unless its parent device is root port, >> + * and it is the only slot directly connected to root port. >> + */ >> + if ((128 << dev->pcie_mpss) >= p_mps) { >> + pcie_write_mps(dev, p_mps); >> + } else if (pci_pcie_type(parent) == PCI_EXP_TYPE_ROOT_PORT && >> + pci_only_one_slot(dev->bus)) { >> + mpss = 128 << dev->pcie_mpss; > > OCD nit, you could move the above line up 4 lines and reuse the > variable in the first if-statement. Good, thanks! > >> + pcie_write_mps(parent, mpss); >> + pcie_write_mps(dev, mpss); >> + } else { >> + dev_warn(&dev->dev, "MPS %d MPSS %d both smaller than upstream MPS %d\n" >> + "If necessary, use \"pci=pcie_bus_peer2peer\" boot parameter to avoid this problem\n", >> + mps, 128 << dev->pcie_mpss, p_mps); >> + } > > Nit, braces are unnecessary in the else. I think > scripts/checkpatch.pl would've complained if you ran it on the patch. I used scripts/checkpatch.pl to check patch, result is ok. So if I use scripts/checkpatch.pl to check patch without the pair braces, and result is ok, I will remove it. Thanks! > > If you/Bjorn want to disregard my paranoia and nits, it looks fine to me. > >> + return 0; >> +} >> + >> +static void pcie_bus_update_setting(struct pci_bus *bus) >> +{ >> + if (bus->self->is_hotplug_bridge) >> + pci_walk_bus(bus, pcie_bus_update_set, NULL); >> +} >> + >> /* pcie_bus_configure_settings requires that pci_walk_bus work in a top-down, >> * parents then children fashion. If this changes, then this code will not >> * work as designed. >> @@ -1632,8 +1671,17 @@ void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss) >> if (!pci_is_pcie(bus->self)) >> return; >> >> - if (pcie_bus_config == PCIE_BUS_TUNE_OFF) >> + if (pcie_bus_config == PCIE_BUS_TUNE_OFF) { >> + /* Sometimes we should update device mps here, >> + * eg. after hot add, device mps value will be >> + * set to default(128B), but the upstream port >> + * mps value may be larger than 128B, if we do >> + * not update the device mps, it maybe can not >> + * work normally. >> + */ >> + pcie_bus_update_setting(bus); >> 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, >> -- >> 1.7.1 >> >> > -- > To unsubscribe from this list: send the line "unsubscribe stable" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > . > -- Thanks! Yijing -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
