Commit 4a9af6cac050 ("ACPI: EC: Rework flushing of EC work while
suspended to idle") made acpi_ec_dispatch_gpe() check
pm_wakeup_pending(), but that is before canceling the SCI wakeup,
so pm_wakeup_pending() is always true.  This causes the loop in
acpi_ec_dispatch_gpe() to always terminate after one iteration which
may not be correct.

Address this issue by canceling the SCI wakeup earlier, from
acpi_ec_dispatch_gpe() itself.

Fixes: 4a9af6cac050 ("ACPI: EC: Rework flushing of EC work while suspended to idle")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Move acpi_ec_create_query() after acpi_ec_event_processor(), drop the
no longer needed forward declaration of the latter, and eliminate
acpi_ec_delete_query() which isn't really necessary.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The EC driver uses a relatively simple state machine for the event
work handling, but it is not really straightforward to figure out.

The states are as follows:

 "Ready": The event handling work can be submitted.

  In this state, the EC_FLAGS_QUERY_PENDING flag is clear.

 "In progress": The event handling work is pending or is being
                processed.  It cannot be submitted again.

  In ths state, the EC_FLAGS_QUERY_PENDING flag is set and both the
  events_to_process count is nonzero and the EC_FLAGS_QUERY_GUARDING
  flag is clear.

 "Complete": The event handling work has been completed, but it still
             cannot be submitted again.

  In ths state, the EC_FLAGS_QUERY_PENDING flag is set and the
  events_to_process count is zero or the EC_FLAGS_QUERY_GUARDING
  flag is set.

The state changes from "Ready" to "In progress" when new event is
detected by advance_transaction() and acpi_ec_submit_event() is
called by it.

Next, the state can change from "In progress" directly to "Ready" in
the following situations:

 * ec_event_clearing is ACPI_EC_EVT_TIMING_STATUS and the state of
   an ACPI_EC_COMMAND_QUERY transaction becomes ACPI_EC_COMMAND_POLL.

 * ec_event_clearing is ACPI_EC_EVT_TIMING_QUERY and the state of
   an ACPI_EC_COMMAND_QUERY transaction becomes
   ACPI_EC_COMMAND_COMPLETE.

 * ec_event_clearing is either ACPI_EC_EVT_TIMING_STATUS or
   ACPI_EC_EVT_TIMING_QUERY and there are no more events to
   process (ie. ec->events_to_process becomes 0).

If ec_event_clearing is ACPI_EC_EVT_TIMING_EVENT, however, the
state must change from "In progress" to "Complete" before it
can change to "Ready".  The changes from "In progress" to
"Complete" in that case occur in the following situations:

 * The state of an ACPI_EC_COMMAND_QUERY transaction becomes
   ACPI_EC_COMMAND_COMPLETE.

 * There are no more events to process (ie. ec->events_to_process
   becomes 0).

Finally, the state changes from "Complete" to "Ready" when
advance_transaction() is invoked when the state is "Complete" and
the state of the current transaction is not ACPI_EC_COMMAND_POLL.

To make this state machine visible in the code, add a new
event_state field to struct acpi_ec and modify the code to use
it istead the EC_FLAGS_QUERY_PENDING and EC_FLAGS_QUERY_GUARDING
flags.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Notice that it is not necessary to queue up the event work again
if the while () loop in acpi_ec_event_handler() is still running
which is the case if nr_pending_queries is greater than 0 at the
beginning of acpi_ec_submit_event() and modify the code to avoid
doing that.

While at it, rename nr_pending_queries in struct acpi_ec to
events_to_process which actually matches the role of that field
and change its data type to unsigned int which is sufficient.

No expected functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Rename acpi_ec_submit_query() to acpi_ec_submit_event(),
acpi_ec_query() to acpi_ec_submit_query(), and
acpi_ec_complete_query() to acpi_ec_close_event() to make
the names reflect what the functions do.

No expected functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Because acpi_ec_event_handler() is a work function, it always
runs in process context with interrupts enabled, so it can use
spin_lock_irq() and spin_unlock_irq() for the locking.

Make it do so and adjust white space around those calls.

No expected functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

It is not necessary to check ec->nr_pending_queries against 0 in the
while () loop in acpi_ec_event_handler(), because that loop terminates
when ec->nr_pending_queries is 0 and the code depending on that can be
run after the loop has ended.

Modify the code accordingly and while at it rewrite the comment
regarding that code to make it clearer.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Because acpi_ec_event_handler() is the only caller of
acpi_ec_check_event() and the separation of these two functions
makes it harder to follow the code flow, fold the latter into the
former (and simplify that code while at it).

No expected functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Notice that the second argument to acpi_ec_query() is redundant,
because in the only case when it is not NULL, the value passed
through it is only checked against 0 and it can only be 0 when
acpi_ec_query() returns an error code, but its return value
is checked along with the value passed through its second
argument.

Accordingly, modify acpi_ec_query() to take only one argument
and while at it, change its handling of the case when
acpi_ec_transaction() returns an error so as to return that
error value to the caller right away.

No expected functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Calling acpi_dispatch_gpe() from acpi_ec_dispatch_gpe() is generally
problematic, because it may cause the spurious interrupt handling in
advance_transaction() to trigger in theory.

However, instead of calling acpi_dispatch_gpe() to dispatch the EC
GPE, acpi_ec_dispatch_gpe() can call advance_transaction() directly
on first_ec and it can pass 'false' as its second argument to indicate
calling it from process context.

Moreover, if advance_transaction() is modified to return a bool value
indicating whether or not the EC work needs to be flushed, it can be
used to avoid unnecessary EC work flushing in acpi_ec_dispatch_gpe(),
so change the code accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>