Many community-driven archives now provide pre-converted PS2 CHD files to save users the conversion time: Internet Archive
However, the user specifically mentioned "ps2 chd roms upd", so maybe they are looking for an update on how to do that, perhaps there's a new way or a recent development allowing CHD for PS2. Maybe a new tool was released. ps2 chd roms upd
Runs flawlessly and is highly recommended to save SD card space. RetroArch (LRPS2): ps2 chd roms upd
CHD offers 40% smaller files than ISO with virtually zero performance penalty. CSO (Compressed ISO) is obsolete for PS2. ps2 chd roms upd