GitLab

The UMP Utility and Stream messages are "groupless", i.e. an incoming
groupless packet should be sent only to the UMP EP port, and the event
with the groupless message is sent to UMP EP as is without the group
translation per port.

Also, the former reserved bit 0 for the client group filter is now
used for groupless events.  When the bit 0 is set, the groupless
events are filtered out and skipped.

Link: https://lore.kernel.org/r/20230612081054.17200-6-tiwai@suse.de

Signed-off-by: Takashi Iwai <tiwai@suse.de>