| Message ID | 1623576555-40338-7-git-send-email-liudongdong3@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | PCI: Enable 10-Bit tag support for PCIe devices | expand |
On Sun, Jun 13, 2021 at 05:29:15PM +0800, Dongdong Liu wrote: > PCIe spec 5.0r1.0 section 2.2.6.2 implementation note, In configurations > where a Requester with 10-Bit Tag Requester capability needs to target > multiple Completers, one needs to ensure that the Requester sends 10-Bit > Tag Requests only to Completers that have 10-Bit Tag Completer capability. > So we enable 10-Bit Tag Requester for root port only when the devices > under the root port support 10-Bit Tag Completer. > > Signed-off-by: Dongdong Liu <liudongdong3@huawei.com> > --- > drivers/pci/pcie/portdrv_pci.c | 75 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 75 insertions(+) > > diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c > index c7ff1ee..baf413f 100644 > --- a/drivers/pci/pcie/portdrv_pci.c > +++ b/drivers/pci/pcie/portdrv_pci.c > @@ -90,6 +90,78 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = { > #define PCIE_PORTDRV_PM_OPS NULL > #endif /* !PM */ > > +static int pci_10bit_tag_comp_support(struct pci_dev *dev, void *data) > +{ > + u8 *support = data; > + > + if (*support == 0) > + return 0; > + > + if (!pci_is_pcie(dev)) { > + *support = 0; > + return 0; > + } > + > + /* > + * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note. > + * For configurations where a Requester with 10-Bit Tag Requester > + * capability targets Completers where some do and some do not have > + * 10-Bit Tag Completer capability, how the Requester determines which > + * NPRs include 10-Bit Tags is outside the scope of this specification. > + * So we do not consider hotplug scenario. > + */ > + if (dev->is_hotplug_bridge) { > + *support = 0; > + return 0; > + } > + > + if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP)) { > + *support = 0; > + return 0; > + } > + > + return 0; > +} > + > +static void pci_configure_rp_10bit_tag(struct pci_dev *dev) > +{ > + u8 support = 1; > + struct pci_dev *pchild; > + > + if (dev->subordinate == NULL) > + return; > + > + /* If no devices under the root port, no need to enable 10-Bit Tag. */ > + pchild = list_first_entry_or_null(&dev->subordinate->devices, > + struct pci_dev, bus_list); > + if (pchild == NULL) > + return; pchild is never used after this check, so this could be simplified to a list_empty(&dev->subordinate->devices).
On 2021/6/14 13:57, Christoph Hellwig wrote: > On Sun, Jun 13, 2021 at 05:29:15PM +0800, Dongdong Liu wrote: >> PCIe spec 5.0r1.0 section 2.2.6.2 implementation note, In configurations >> where a Requester with 10-Bit Tag Requester capability needs to target >> multiple Completers, one needs to ensure that the Requester sends 10-Bit >> Tag Requests only to Completers that have 10-Bit Tag Completer capability. >> So we enable 10-Bit Tag Requester for root port only when the devices >> under the root port support 10-Bit Tag Completer. >> >> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com> >> --- >> drivers/pci/pcie/portdrv_pci.c | 75 ++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 75 insertions(+) >> >> diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c >> index c7ff1ee..baf413f 100644 >> --- a/drivers/pci/pcie/portdrv_pci.c >> +++ b/drivers/pci/pcie/portdrv_pci.c >> @@ -90,6 +90,78 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = { >> #define PCIE_PORTDRV_PM_OPS NULL >> #endif /* !PM */ >> >> +static int pci_10bit_tag_comp_support(struct pci_dev *dev, void *data) >> +{ >> + u8 *support = data; >> + >> + if (*support == 0) >> + return 0; >> + >> + if (!pci_is_pcie(dev)) { >> + *support = 0; >> + return 0; >> + } >> + >> + /* >> + * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note. >> + * For configurations where a Requester with 10-Bit Tag Requester >> + * capability targets Completers where some do and some do not have >> + * 10-Bit Tag Completer capability, how the Requester determines which >> + * NPRs include 10-Bit Tags is outside the scope of this specification. >> + * So we do not consider hotplug scenario. >> + */ >> + if (dev->is_hotplug_bridge) { >> + *support = 0; >> + return 0; >> + } >> + >> + if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP)) { >> + *support = 0; >> + return 0; >> + } >> + >> + return 0; >> +} >> + >> +static void pci_configure_rp_10bit_tag(struct pci_dev *dev) >> +{ >> + u8 support = 1; >> + struct pci_dev *pchild; >> + >> + if (dev->subordinate == NULL) >> + return; >> + >> + /* If no devices under the root port, no need to enable 10-Bit Tag. */ >> + pchild = list_first_entry_or_null(&dev->subordinate->devices, >> + struct pci_dev, bus_list); >> + if (pchild == NULL) >> + return; > > pchild is never used after this check, so this could be simplified to > a list_empty(&dev->subordinate->devices). Good point, will do. Thanks, Dongdong > . >
diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c index c7ff1ee..baf413f 100644 --- a/drivers/pci/pcie/portdrv_pci.c +++ b/drivers/pci/pcie/portdrv_pci.c @@ -90,6 +90,78 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = { #define PCIE_PORTDRV_PM_OPS NULL #endif /* !PM */ +static int pci_10bit_tag_comp_support(struct pci_dev *dev, void *data) +{ + u8 *support = data; + + if (*support == 0) + return 0; + + if (!pci_is_pcie(dev)) { + *support = 0; + return 0; + } + + /* + * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note. + * For configurations where a Requester with 10-Bit Tag Requester + * capability targets Completers where some do and some do not have + * 10-Bit Tag Completer capability, how the Requester determines which + * NPRs include 10-Bit Tags is outside the scope of this specification. + * So we do not consider hotplug scenario. + */ + if (dev->is_hotplug_bridge) { + *support = 0; + return 0; + } + + if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP)) { + *support = 0; + return 0; + } + + return 0; +} + +static void pci_configure_rp_10bit_tag(struct pci_dev *dev) +{ + u8 support = 1; + struct pci_dev *pchild; + + if (dev->subordinate == NULL) + return; + + /* If no devices under the root port, no need to enable 10-Bit Tag. */ + pchild = list_first_entry_or_null(&dev->subordinate->devices, + struct pci_dev, bus_list); + if (pchild == NULL) + return; + + pci_10bit_tag_comp_support(dev, &support); + if (!support) + return; + + /* + * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note. + * In configurations where a Requester with 10-Bit Tag Requester + * capability needs to target multiple Completers, one needs to ensure + * that the Requester sends 10-Bit Tag Requests only to Completers + * that have 10-Bit Tag Completer capability. So we enable 10-Bit Tag + * Requester for root port only when the devices under the root port + * support 10-Bit Tag Completer. + */ + pci_walk_bus(dev->subordinate, pci_10bit_tag_comp_support, &support); + if (!support) + return; + + if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_REQ)) + return; + + pci_dbg(dev, "enabling 10-Bit Tag Requester\n"); + pcie_capability_set_word(dev, PCI_EXP_DEVCTL2, + PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN); +} + /* * pcie_portdrv_probe - Probe PCI-Express port devices * @dev: PCI-Express port device being probed @@ -111,6 +183,9 @@ static int pcie_portdrv_probe(struct pci_dev *dev, (type != PCI_EXP_TYPE_RC_EC))) return -ENODEV; + if (type == PCI_EXP_TYPE_ROOT_PORT) + pci_configure_rp_10bit_tag(dev); + if (type == PCI_EXP_TYPE_RC_EC) pcie_link_rcec(dev);
PCIe spec 5.0r1.0 section 2.2.6.2 implementation note, In configurations where a Requester with 10-Bit Tag Requester capability needs to target multiple Completers, one needs to ensure that the Requester sends 10-Bit Tag Requests only to Completers that have 10-Bit Tag Completer capability. So we enable 10-Bit Tag Requester for root port only when the devices under the root port support 10-Bit Tag Completer. Signed-off-by: Dongdong Liu <liudongdong3@huawei.com> --- drivers/pci/pcie/portdrv_pci.c | 75 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+)