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@xxxxxxxxxx> --- 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
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