Messages in this thread | | | Date | Wed, 7 Sep 2022 23:11:09 -0700 | From | Dan Williams <> | Subject | RE: [PATCH 05/15] cxl/acpi: Add probe function to detect restricted CXL hosts in RCD mode |
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Robert Richter wrote: > Restricted CXL device (RCD) mode (formerly CXL 1.1) uses a different > enumeration scheme other than CXL VH (formerly CXL 2.0). In RCD mode a > host/device (RCH-RCD) pair shows up as a legal PCIe hierarchy with an > ACPI host bridge ("PNP0A08" or "ACPI0016" HID) and RCiEP connected to > it with a description of the CXL device. > > Add function cxl_restricted_host_probe() to probe RCD enumerated > devices. The function implements a loop that detects all CXL capable > ACPI PCI root bridges in the system (RCD mode only). The iterator > function cxl_find_next_rch() is introduced to walk through all of the > CXL hosts. The loop will then enable all CXL devices connected to the > host. For now, only implement an empty loop with an iterator that > returns all pci host bridges in the system. > > The probe function is triggered by adding an own root device for RCHs. > This is different to CXL VH where an ACPI "ACPI0017" root device > exists. Its detection starts the CXL host detection. In RCD mode such > a device does not necessarily exists, so solve this by creating a > plain platform device that is not an ACPI device and is root only for > RCHs.
These host bridges should be discovered by add_host_bridge_dport(), no? Unless the BIOS is failing to emit the expected CEDT along with ACPI0017.
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