HID: intel-ish-hid: Use dedicated unbound workqueues to prevent resume blocking

During suspend/resume tests with S2IDLE, some ISH functional failures were
observed because of delay in executing ISH resume handler. Here
schedule_work() is used from resume handler to do actual work.
schedule_work() uses system_wq, which is a per CPU work queue. Although
the queuing is not bound to a CPU, but it prefers local CPU of the caller,
unless prohibited.

Users of this work queue are not supposed to queue long running work.
But in practice, there are scenarios where long running work items are
queued on other unbound workqueues, occupying the CPU. As a result, the
ISH resume handler may not get a chance to execute in a timely manner.

In one scenario, one of the ish_resume_handler() executions was delayed
nearly 1 second because another work item on an unbound workqueue occupied
the same CPU. This delay causes ISH functionality failures.

A similar issue was previously observed where the ISH HID driver timed out
while getting the HID descriptor during S4 resume in the recovery kernel,
likely caused by the same workqueue contention problem.

Create dedicated unbound workqueues for all ISH operations to allow work
items to execute on any available CPU, eliminating CPU-specific bottlenecks
and improving resume reliability under varying system loads. Also ISH has
three different components, a bus driver which implements ISH protocols, a
PCI interface layer and HID interface. Use one dedicated work queue for all
of them.

Signed-off-by: Zhang Lixu <lixu.zhang@intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

0 files changed, 0 insertions, 0 deletions