msm: pil: Synchronize request_firmware() with suspend
Calling request_firmware() during suspend/resume operations is
buggy and error prone. Therefore a check exists in
request_firmware() to see if a suspend/resume operation is in
progress. In testing we've seen that a wakeup interrupt can come
in during suspend and trigger subsystem restart to call
pil_force_boot() before userspace has fully thawed. Since this is
not allowed the request_firmware() call from pil_force_boot()
fails with -EBUSY and the processor is never rebooted.
Register for PM notifiers to avoid calling request_firmware()
when suspend/resume is in progress. Within the notifier
synchronize any request firmware calls with suspend using a
rwsem. In the case where pil is called before suspend, the
suspend notifier should block on the down_write() during
PM_SUSPEND_PREPARE. When suspend is initiated before pil any pil
operations should block on the down_read() until suspend
finishes. Doing this should fix races between suspend/resume and
request_firmware() within PIL.
Change-Id: I8dcafcac5be80ef41d00bca9b8509652ad1108cc
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
1 file changed