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>>>> } >>>> >>>> +bool pcie_is_cxl_port(struct pci_dev *dev) >>>> +{ >>>> + if (!pcie_is_cxl(dev)) >>>> + return false; >>>> + >>>> + if ((pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT) && >>>> + (pci_pcie_type(dev) != PCI_EXP_TYPE_UPSTREAM) && >>>> + (pci_pcie_type(dev) != PCI_EXP_TYPE_DOWNSTREAM)) >>>> + return false; >>>> + >>>> + return cxl_port_dvsec(dev); >>>> +} >>>> +EXPORT_SYMBOL_GPL(pcie_is_cxl_port); >>> The "!pcie_is_cxl(dev)" check at the top of the function is identical >>> to the return value "cxl_port_dvsec(dev)". This looks redundant. >>> However one cannot call pci_pcie_type() without first checking >>> pci_is_pcie(). So I'm wondering if the "!pcie_is_cxl(dev)" check >>> is actually erroneous and supposed to be "!pci_is_pcie(dev)"? >>> That would make more sense to me. >> I see pcie_is_cxl(dev) is different than cxl_port_dvsec(dev). >> They check different DVSECs. > Ah, sorry, I missed that. > >> CXL flexbus DVSEC presence is cached in pci_dev::is_cxl and returned by >> pcie_is_cxl(). This is used for indicating CXL device. >> >> cxl_port_dvsec(dev) returns boolean based on presence of CXL port DVSEC to >> indicate a CXL port device. >> >> I don't believe they are redundant if you consider you can have a CXL >> device that >> is not a CXL port device. > Can you have a CXL port that is not a CXL device? > > If not, it would seem to me that checking for Flexbus DVSEC presence > *is* redundant. Or do you anticipate broken devices which lack the > Flexbus DVSEC and that you explicitly want to exclude? > > Thanks, > > Lukas No, the CXL port device is always a CXL device per spec. This was added to short-circuit the function by returning immediately if the device is _not_ a CXL device. Otherwise for PCIe Port devices, the CXL Port DVSEC will be searched. I was trying to avoid the unnecessary CXL port DVSEC search unless the other criteria are met. And I expect most cases will not be a CXL device. I will remove the "if (!pcie_is_cxl(dev))" block as you suggested. Regards, Terry