Hi Shrihari, The switch/HB write mask opens UIG and UIW, but leaves ISP read-only. CXL 3.2 section 8.2.4.20.7 makes ISP writable on a UIO-capable switch or Host Bridge too.
With two UIO-enabled host bridges in a two-way CFMWS (4 KiB granularity), the switch below the second HB advertises UIO, but writing decoder 0 Control with UIO=1, UIG=4, UIW=1 (two ways), ISP=1 reads back 0x00144000 rather than 0x01144000. Software cannot configure the second position in the interleave set. Could R_CXL_HDM_DECODER0_CTRL_ISP_MASK be included alongside UIG and UIW in that switch/HB branch? It may also be worth diagnosing a partially configured host bridge: with x-uio=on and two RPs, one without SVC/flit, the HB reads 0x22382 but that RP reads 0x312. The HB UIO bit is defined to cover all its root ports (8.2.4.20.1). A warning would make this inconsistent setup easier to spot. Many thanks, Junjie
