2 files changed, 66 insertions, 3 deletions

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index a6179b71c573..1fa14634c3f6 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -145,6 +145,11 @@ static bool acpi_ec_started(struct acpi_ec *ec)
                !test_bit(EC_FLAGS_STOPPED, &ec->flags);
 }
 
+static bool acpi_ec_flushed(struct acpi_ec *ec)
+{
+        return ec->reference_count == 1;
+}
+
 /* --------------------------------------------------------------------------
  *                           EC Registers
  * -------------------------------------------------------------------------- */
@@ -266,6 +271,44 @@ static inline void acpi_ec_clear_gpe(struct acpi_ec *ec)
  *                           Transaction Management
  * -------------------------------------------------------------------------- */
 
+static void acpi_ec_submit_request(struct acpi_ec *ec)
+{
+        ec->reference_count++;
+        if (ec->reference_count == 1)
+                acpi_ec_enable_gpe(ec, true);
+}
+
+static void acpi_ec_complete_request(struct acpi_ec *ec)
+{
+        bool flushed = false;
+
+        ec->reference_count--;
+        if (ec->reference_count == 0)
+                acpi_ec_disable_gpe(ec, true);
+        flushed = acpi_ec_flushed(ec);
+        if (flushed)
+                wake_up(&ec->wait);
+}
+
+/*
+ * acpi_ec_submit_flushable_request() - Increase the reference count unless
+ *                                      the flush operation is not in
+ *                                      progress
+ * @ec: the EC device
+ *
+ * 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.
+ */
+static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
+{
+        if (!acpi_ec_started(ec))
+                return false;
+        acpi_ec_submit_request(ec);
+        return true;
+}
+
 static void acpi_ec_submit_query(struct acpi_ec *ec)
 {
         if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
@@ -426,7 +469,8 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
                 udelay(ACPI_EC_MSI_UDELAY);
         /* start transaction */
         spin_lock_irqsave(&ec->lock, tmp);
-        if (!acpi_ec_started(ec)) {
+        /* Enable GPE for command processing (IBF=0/OBF=1) */
+        if (!acpi_ec_submit_flushable_request(ec)) {
                 ret = -EINVAL;
                 goto unlock;
         }
@@ -441,6 +485,8 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
         pr_debug("***** Command(%s) stopped *****\n",
                  acpi_ec_cmd_string(t->command));
         ec->curr = NULL;
+        /* Disable GPE for command processing (IBF=0/OBF=1) */
+        acpi_ec_complete_request(ec);
 unlock:
         spin_unlock_irqrestore(&ec->lock, tmp);
         return ret;
@@ -614,13 +660,25 @@ static void acpi_ec_start(struct acpi_ec *ec, bool resuming)
         spin_lock_irqsave(&ec->lock, flags);
         if (!test_and_set_bit(EC_FLAGS_STARTED, &ec->flags)) {
                 pr_debug("+++++ Starting EC +++++\n");
+                /* Enable GPE for event processing (SCI_EVT=1) */
                 if (!resuming)
-                        acpi_ec_enable_gpe(ec, true);
+                        acpi_ec_submit_request(ec);
                 pr_info("+++++ EC started +++++\n");
         }
         spin_unlock_irqrestore(&ec->lock, flags);
 }
 
+static bool acpi_ec_stopped(struct acpi_ec *ec)
+{
+        unsigned long flags;
+        bool flushed;
+
+        spin_lock_irqsave(&ec->lock, flags);
+        flushed = acpi_ec_flushed(ec);
+        spin_unlock_irqrestore(&ec->lock, flags);
+        return flushed;
+}
+
 static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)
 {
         unsigned long flags;
@@ -629,8 +687,12 @@ static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)
         if (acpi_ec_started(ec)) {
                 pr_debug("+++++ Stopping EC +++++\n");
                 set_bit(EC_FLAGS_STOPPED, &ec->flags);
+                spin_unlock_irqrestore(&ec->lock, flags);
+                wait_event(ec->wait, acpi_ec_stopped(ec));
+                spin_lock_irqsave(&ec->lock, flags);
+                /* Disable GPE for event processing (SCI_EVT=1) */
                 if (!suspending)
-                        acpi_ec_disable_gpe(ec, true);
+                        acpi_ec_complete_request(ec);
                 clear_bit(EC_FLAGS_STARTED, &ec->flags);
                 clear_bit(EC_FLAGS_STOPPED, &ec->flags);
                 pr_info("+++++ EC stopped +++++\n");
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index dc420787ffcd..7dc69d82f658 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -122,6 +122,7 @@ struct acpi_ec {
         unsigned long data_addr;
         unsigned long global_lock;
         unsigned long flags;
+        unsigned long reference_count;
         struct mutex mutex;
         wait_queue_head_t wait;
         struct list_head list;