[PATCH 02/10] ACPI: EC: Call advance_transaction() from acpi_ec_dispatch_gpe()

Rafael J. Wysocki
2021-11-23T18:49:40Z

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>
---
drivers/acpi/ec.c | 39 ++++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)

Index: linux-pm/drivers/acpi/ec.c
===================================================================
--- linux-pm.orig/drivers/acpi/ec.c
+++ linux-pm/drivers/acpi/ec.c
@@ -170,7 +170,7 @@ struct acpi_ec_query {
};

static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
-static void advance_transaction(struct acpi_ec *ec, bool interrupt);
+static bool advance_transaction(struct acpi_ec *ec, bool interrupt);
static void acpi_ec_event_handler(struct work_struct *work);
static void acpi_ec_event_processor(struct work_struct *work);

@@ -444,18 +444,25 @@ static bool acpi_ec_submit_flushable_req
return true;
}

-static void acpi_ec_submit_query(struct acpi_ec *ec)
+static bool acpi_ec_submit_query(struct acpi_ec *ec)
{
acpi_ec_mask_events(ec);
if (!acpi_ec_event_enabled(ec))
- return;
+ return false;
+
if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
ec_dbg_evt("Command(%s) submitted/blocked",
acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
ec->nr_pending_queries++;
ec->events_in_progress++;
- queue_work(ec_wq, &ec->work);
+ return queue_work(ec_wq, &ec->work);
}
+
+ /*
+ * The event handling work has not been completed yet, so it needs to be
+ * flushed.
+ */
+ return true;
}

static void acpi_ec_complete_query(struct acpi_ec *ec)
@@ -628,10 +635,11 @@ static void acpi_ec_spurious_interrupt(s
acpi_ec_mask_events(ec);
}

-static void advance_transaction(struct acpi_ec *ec, bool interrupt)
+static bool advance_transaction(struct acpi_ec *ec, bool interrupt)
{
struct transaction *t = ec->curr;
bool wakeup = false;
+ bool ret = false;
u8 status;

ec_dbg_stm("%s (%d)", interrupt ? "IRQ" : "TASK", smp_processor_id());
@@ -698,10 +706,12 @@ static void advance_transaction(struct a

out:
if (status & ACPI_EC_FLAG_SCI)
- acpi_ec_submit_query(ec);
+ ret = acpi_ec_submit_query(ec);

if (wakeup && interrupt)
wake_up(&ec->wait);
+
+ return ret;
}

static void start_transaction(struct acpi_ec *ec)
@@ -2038,8 +2048,7 @@ void acpi_ec_set_gpe_wake_mask(u8 action

bool acpi_ec_dispatch_gpe(void)
{
- bool work_in_progress;
- u32 ret;
+ bool work_in_progress = false;

if (!first_ec)
return acpi_any_gpe_status_set(U32_MAX);
@@ -2055,9 +2064,17 @@ bool acpi_ec_dispatch_gpe(void)
* Dispatch the EC GPE in-band, but do not report wakeup in any case
* to allow the caller to process events properly after that.
*/
- ret = acpi_dispatch_gpe(NULL, first_ec->gpe);
- if (ret == ACPI_INTERRUPT_HANDLED)
- pm_pr_dbg("ACPI EC GPE dispatched\n");
+ spin_lock_irq(&first_ec->lock);
+
+ if (acpi_ec_gpe_status_set(first_ec))
+ work_in_progress = advance_transaction(first_ec, false);
+
+ spin_unlock_irq(&first_ec->lock);
+
+ if (!work_in_progress)
+ return false;
+
+ pm_pr_dbg("ACPI EC GPE dispatched\n");

/* Drain EC work. */
do {