Revert "ACPI / EC: Add query flushing support"

Revert commit f252cb09 (ACPI / EC: Add query flushing support),
because it breaks system suspend on Acer Aspire S5.  The machine
just hangs solid at the last stage of suspend (after taking non-boot
CPUs offline).
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/ec.c

@@ -76,9 +76,7 @@ enum ec_command {
 					 * when trying to clear the EC */
 
 enum {
-	EC_FLAGS_EVENT_ENABLED,		/* Event is enabled */
-	EC_FLAGS_EVENT_PENDING,		/* Event is pending */
-	EC_FLAGS_EVENT_DETECTED,	/* Event is detected */
+	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
 	EC_FLAGS_HANDLERS_INSTALLED,	/* Handlers for GPE and
 					 * OpReg are installed */
 	EC_FLAGS_STARTED,		/* Driver is started */
@@ -153,12 +151,6 @@ static bool acpi_ec_flushed(struct acpi_ec *ec)
 	return ec->reference_count == 1;
 }
 
-static bool acpi_ec_has_pending_event(struct acpi_ec *ec)
-{
-	return test_bit(EC_FLAGS_EVENT_DETECTED, &ec->flags) ||
-	       test_bit(EC_FLAGS_EVENT_PENDING, &ec->flags);
-}
-
 /* --------------------------------------------------------------------------
  *                           EC Registers
  * -------------------------------------------------------------------------- */
@@ -326,93 +318,36 @@ static void acpi_ec_clear_storm(struct acpi_ec *ec, u8 flag)
  *                                      the flush operation is not in
  *                                      progress
  * @ec: the EC device
- * @allow_event: whether event should be handled
  *
  * This function must be used before taking a new action that should hold
  * the reference count.  If this function returns false, then the action
  * must be discarded or it will prevent the flush operation from being
  * completed.
- *
- * During flushing, QR_EC command need to pass this check when there is a
- * pending event, so that the reference count held for the pending event
- * can be decreased by the completion of the QR_EC command.
  */
-static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec,
-					     bool allow_event)
+static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
 {
-	if (!acpi_ec_started(ec)) {
-		if (!allow_event || !acpi_ec_has_pending_event(ec))
-			return false;
-	}
+	if (!acpi_ec_started(ec))
+		return false;
 	acpi_ec_submit_request(ec);
 	return true;
 }
 
-static void acpi_ec_submit_event(struct acpi_ec *ec)
+static void acpi_ec_submit_query(struct acpi_ec *ec)
 {
-	if (!test_bit(EC_FLAGS_EVENT_DETECTED, &ec->flags) ||
-	    !test_bit(EC_FLAGS_EVENT_ENABLED, &ec->flags))
-		return;
-	/* Hold reference for pending event */
-	if (!acpi_ec_submit_flushable_request(ec, true))
-		return;
-	if (!test_and_set_bit(EC_FLAGS_EVENT_PENDING, &ec->flags)) {
-		pr_debug("***** Event query started *****\n");
+	if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
+		pr_debug("***** Event started *****\n");
 		schedule_work(&ec->work);
-		return;
-	}
-	acpi_ec_complete_request(ec);
-}
-
-static void acpi_ec_complete_event(struct acpi_ec *ec)
-{
-	if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
-		clear_bit(EC_FLAGS_EVENT_PENDING, &ec->flags);
-		pr_debug("***** Event query stopped *****\n");
-		/* Unhold reference for pending event */
-		acpi_ec_complete_request(ec);
-		/* Check if there is another SCI_EVT detected */
-		acpi_ec_submit_event(ec);
-	}
-}
-
-static void acpi_ec_submit_detection(struct acpi_ec *ec)
-{
-	/* Hold reference for query submission */
-	if (!acpi_ec_submit_flushable_request(ec, false))
-		return;
-	if (!test_and_set_bit(EC_FLAGS_EVENT_DETECTED, &ec->flags)) {
-		pr_debug("***** Event detection blocked *****\n");
-		acpi_ec_submit_event(ec);
-		return;
 	}
-	acpi_ec_complete_request(ec);
 }
 
-static void acpi_ec_complete_detection(struct acpi_ec *ec)
+static void acpi_ec_complete_query(struct acpi_ec *ec)
 {
 	if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
-		clear_bit(EC_FLAGS_EVENT_DETECTED, &ec->flags);
-		pr_debug("***** Event detetion unblocked *****\n");
-		/* Unhold reference for query submission */
-		acpi_ec_complete_request(ec);
+		clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
+		pr_debug("***** Event stopped *****\n");
 	}
 }
 
-static void acpi_ec_enable_event(struct acpi_ec *ec)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&ec->lock, flags);
-	set_bit(EC_FLAGS_EVENT_ENABLED, &ec->flags);
-	/*
-	 * An event may be pending even with SCI_EVT=0, so QR_EC should
-	 * always be issued right after started.
-	 */
-	acpi_ec_submit_detection(ec);
-	spin_unlock_irqrestore(&ec->lock, flags);
-}
-
 static int ec_transaction_completed(struct acpi_ec *ec)
 {
 	unsigned long flags;
@@ -454,7 +389,6 @@ static void advance_transaction(struct acpi_ec *ec)
 				t->rdata[t->ri++] = acpi_ec_read_data(ec);
 				if (t->rlen == t->ri) {
 					t->flags |= ACPI_EC_COMMAND_COMPLETE;
-					acpi_ec_complete_event(ec);
 					if (t->command == ACPI_EC_COMMAND_QUERY)
 						pr_debug("***** Command(%s) hardware completion *****\n",
 							 acpi_ec_cmd_string(t->command));
@@ -465,7 +399,6 @@ static void advance_transaction(struct acpi_ec *ec)
 		} else if (t->wlen == t->wi &&
 			   (status & ACPI_EC_FLAG_IBF) == 0) {
 			t->flags |= ACPI_EC_COMMAND_COMPLETE;
-			acpi_ec_complete_event(ec);
 			wakeup = true;
 		}
 		goto out;
@@ -474,17 +407,16 @@ static void advance_transaction(struct acpi_ec *ec)
 		    !(status & ACPI_EC_FLAG_SCI) &&
 		    (t->command == ACPI_EC_COMMAND_QUERY)) {
 			t->flags |= ACPI_EC_COMMAND_POLL;
-			acpi_ec_complete_detection(ec);
+			acpi_ec_complete_query(ec);
 			t->rdata[t->ri++] = 0x00;
 			t->flags |= ACPI_EC_COMMAND_COMPLETE;
-			acpi_ec_complete_event(ec);
 			pr_debug("***** Command(%s) software completion *****\n",
 				 acpi_ec_cmd_string(t->command));
 			wakeup = true;
 		} else if ((status & ACPI_EC_FLAG_IBF) == 0) {
 			acpi_ec_write_cmd(ec, t->command);
 			t->flags |= ACPI_EC_COMMAND_POLL;
-			acpi_ec_complete_detection(ec);
+			acpi_ec_complete_query(ec);
 		} else
 			goto err;
 		goto out;
@@ -505,7 +437,7 @@ static void advance_transaction(struct acpi_ec *ec)
 	}
 out:
 	if (status & ACPI_EC_FLAG_SCI)
-		acpi_ec_submit_detection(ec);
+		acpi_ec_submit_query(ec);
 	if (wakeup && in_interrupt())
 		wake_up(&ec->wait);
 }
@@ -566,7 +498,7 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
 	/* start transaction */
 	spin_lock_irqsave(&ec->lock, tmp);
 	/* Enable GPE for command processing (IBF=0/OBF=1) */
-	if (!acpi_ec_submit_flushable_request(ec, true)) {
+	if (!acpi_ec_submit_flushable_request(ec)) {
 		ret = -EINVAL;
 		goto unlock;
 	}
@@ -947,9 +879,7 @@ static void acpi_ec_gpe_poller(struct work_struct *work)
 {
 	struct acpi_ec *ec = container_of(work, struct acpi_ec, work);
 
-	pr_debug("***** Event poller started *****\n");
 	acpi_ec_query(ec, NULL);
-	pr_debug("***** Event poller stopped *****\n");
 }
 
 static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
@@ -1019,6 +949,7 @@ static struct acpi_ec *make_acpi_ec(void)
 
 	if (!ec)
 		return NULL;
+	ec->flags = 1 << EC_FLAGS_QUERY_PENDING;
 	mutex_init(&ec->mutex);
 	init_waitqueue_head(&ec->wait);
 	INIT_LIST_HEAD(&ec->list);
@@ -1169,7 +1100,7 @@ static int acpi_ec_add(struct acpi_device *device)
 	ret = ec_install_handlers(ec);
 
 	/* EC is fully operational, allow queries */
-	acpi_ec_enable_event(ec);
+	clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
 
 	/* Clear stale _Q events if hardware might require that */
 	if (EC_FLAGS_CLEAR_ON_RESUME)