Re: [PATCH v4 0/5] soundwire: Fixes for spurious and missing UNATTACH
From: Vinod Koul
Date: Tue Sep 20 2022 - 01:00:00 EST
On 14-09-22, 17:02, Richard Fitzgerald wrote:
> 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.
Applied, thanks
--
~Vinod