On Thu, Nov 14, 2024 at 11:07:26AM -0600, Bowman, Terry wrote: > > 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? > > 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. Ah, this is meant as a speed-up. Actually that makes sense, so feel free to keep it. If you do remove it, I think you'll have to move the cxl_port_dvsec() invocation up in the function, in front of the pci_pcie_type() checks. The latter require that one first checks that the device is PCIe. That's done implicitly by cxl_port_dvsec() because it returns 0 in the non-PCIe case. (Due to the "if (dev->cfg_size <= PCI_CFG_SPACE_SIZE)" check in pci_find_next_ext_capability().) Another idea would be to put a "if (!pcie_is_cxl(dev)) return 0;" speed-up in cxl_port_dvsec() so that the other caller benefits from it as well. Thanks, Lukas
