The bus and cadence code has several bugs that cause UNATTACH notifications to either be sent spuriously or to be missed.
These can be seen occasionally with a single peripheral on the bus, but are much more frequent with multiple peripherals, where several peripherals could change state and report in consecutive PINGs.
The root of all of these bugs seems to be a code design flaw that assumed every PING status change would be handled separately. However, PINGs are handled by a workqueue function and there is no guarantee when that function will be scheduled to run or how much CPU time it will receive. PINGs will continue while the work function is handling a snapshot of a previous PING so the code must take account that (a) status could change during the work function and (b) there can be a backlog of changes before the IRQ work function runs again.
Tested with 4 peripherals on 1 bus, and 8 peripherals on 2 buses.
CHANGES SINCE V2: #4 Add a comment explaining why INTMASK isn't cleared when going around the update_status loop.
#5 Leave the existing error handling in sdw_program_device_num(), instead of suppressing the error return. Add a comment in sdw_handle_slave_status() explaining why the error is ignored. Re-word the explanation of why sdw_handle_slave_status() must only return early if it programmed a device ID.
Richard Fitzgerald (4): soundwire: bus: Don't lose unattach notifications soundwire: bus: Don't re-enumerate before status is UNATTACHED soundwire: cadence: Fix lost ATTACHED interrupts when enumerating soundwire: bus: Don't exit early if no device IDs were programmed
Simon Trimmer (1): soundwire: cadence: fix updating slave status when a bus has multiple peripherals
drivers/soundwire/bus.c | 44 +++++++++++++--- drivers/soundwire/cadence_master.c | 80 ++++++++++++++++-------------- 2 files changed, 80 insertions(+), 44 deletions(-)