ACPI: EC: Accelerate query execution

Split EC query handling into acknowledge and execution phase.
This allows much smaller pending query lattency and lowers chances
of EC going "wild" and losing events.

Reference: http://bugzilla.kernel.org/show_bug.cgi?id=14858

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 77 insertions, 45 deletions

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index fd1801bdee66..9cc38857c33b 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -201,14 +201,13 @@ unlock:
         spin_unlock_irqrestore(&ec->curr_lock, flags);
 }
 
-static void acpi_ec_gpe_query(void *ec_cxt);
+static int acpi_ec_sync_query(struct acpi_ec *ec);
 
-static int ec_check_sci(struct acpi_ec *ec, u8 state)
+static int ec_check_sci_sync(struct acpi_ec *ec, u8 state)
 {
         if (state & ACPI_EC_FLAG_SCI) {
                 if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
-                        return acpi_os_execute(OSL_EC_BURST_HANDLER,
-                                acpi_ec_gpe_query, ec);
+                        return acpi_ec_sync_query(ec);
         }
         return 0;
 }
@@ -249,11 +248,6 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
 {
         unsigned long tmp;
         int ret = 0;
-        pr_debug(PREFIX "transaction start\n");
-        /* disable GPE during transaction if storm is detected */
-        if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
-                acpi_disable_gpe(NULL, ec->gpe);
-        }
         if (EC_FLAGS_MSI)
                 udelay(ACPI_EC_MSI_UDELAY);
         /* start transaction */
@@ -269,16 +263,6 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
         spin_lock_irqsave(&ec->curr_lock, tmp);
         ec->curr = NULL;
         spin_unlock_irqrestore(&ec->curr_lock, tmp);
-        if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
-                /* check if we received SCI during transaction */
-                ec_check_sci(ec, acpi_ec_read_status(ec));
-                /* it is safe to enable GPE outside of transaction */
-                acpi_enable_gpe(NULL, ec->gpe);
-        } else if (t->irq_count > ACPI_EC_STORM_THRESHOLD) {
-                pr_info(PREFIX "GPE storm detected, "
-                        "transactions will use polling mode\n");
-                set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
-        }
         return ret;
 }
 
@@ -321,7 +305,24 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
                 status = -ETIME;
                 goto end;
         }
+        pr_debug(PREFIX "transaction start\n");
+        /* disable GPE during transaction if storm is detected */
+        if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+                acpi_disable_gpe(NULL, ec->gpe);
+        }
+
         status = acpi_ec_transaction_unlocked(ec, t);
+
+        /* check if we received SCI during transaction */
+        ec_check_sci_sync(ec, acpi_ec_read_status(ec));
+        if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+                /* it is safe to enable GPE outside of transaction */
+                acpi_enable_gpe(NULL, ec->gpe);
+        } else if (t->irq_count > ACPI_EC_STORM_THRESHOLD) {
+                pr_info(PREFIX "GPE storm detected, "
+                        "transactions will use polling mode\n");
+                set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
+        }
 end:
         if (ec->global_lock)
                 acpi_release_global_lock(glk);
@@ -443,7 +444,7 @@ int ec_transaction(u8 command,
 
 EXPORT_SYMBOL(ec_transaction);
 
-static int acpi_ec_query(struct acpi_ec *ec, u8 * data)
+static int acpi_ec_query_unlocked(struct acpi_ec *ec, u8 * data)
 {
         int result;
         u8 d;
@@ -452,20 +453,16 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 * data)
                                 .wlen = 0, .rlen = 1};
         if (!ec || !data)
                 return -EINVAL;
-
         /*
          * Query the EC to find out which _Qxx method we need to evaluate.
          * Note that successful completion of the query causes the ACPI_EC_SCI
          * bit to be cleared (and thus clearing the interrupt source).
          */
-
-        result = acpi_ec_transaction(ec, &t);
+        result = acpi_ec_transaction_unlocked(ec, &t);
         if (result)
                 return result;
-
         if (!d)
                 return -ENODATA;
-
         *data = d;
         return 0;
 }
@@ -509,43 +506,78 @@ void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
 
 EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
 
-static void acpi_ec_gpe_query(void *ec_cxt)
+static void acpi_ec_run(void *cxt)
 {
-        struct acpi_ec *ec = ec_cxt;
-        u8 value = 0;
-        struct acpi_ec_query_handler *handler, copy;
-
-        if (!ec || acpi_ec_query(ec, &value))
+        struct acpi_ec_query_handler *handler = cxt;
+        if (!handler)
                 return;
-        mutex_lock(&ec->lock);
+        pr_debug(PREFIX "start query execution\n");
+        if (handler->func)
+                handler->func(handler->data);
+        else if (handler->handle)
+                acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
+        pr_debug(PREFIX "stop query execution\n");
+        kfree(handler);
+}
+
+static int acpi_ec_sync_query(struct acpi_ec *ec)
+{
+        u8 value = 0;
+        int status;
+        struct acpi_ec_query_handler *handler, *copy;
+        if ((status = acpi_ec_query_unlocked(ec, &value)))
+                return status;
         list_for_each_entry(handler, &ec->list, node) {
                 if (value == handler->query_bit) {
                         /* have custom handler for this bit */
-                        memcpy(&copy, handler, sizeof(copy));
-                        mutex_unlock(&ec->lock);
-                        if (copy.func) {
-                                copy.func(copy.data);
-                        } else if (copy.handle) {
-                                acpi_evaluate_object(copy.handle, NULL, NULL, NULL);
-                        }
-                        return;
+                        copy = kmalloc(sizeof(*handler), GFP_KERNEL);
+                        if (!copy)
+                                return -ENOMEM;
+                        memcpy(copy, handler, sizeof(*copy));
+                        pr_debug(PREFIX "push query execution (0x%2x) on queue\n", value);
+                        return acpi_os_execute(OSL_GPE_HANDLER,
+                                acpi_ec_run, copy);
                 }
         }
+        return 0;
+}
+
+static void acpi_ec_gpe_query(void *ec_cxt)
+{
+        struct acpi_ec *ec = ec_cxt;
+        if (!ec)
+                return;
+        mutex_lock(&ec->lock);
+        acpi_ec_sync_query(ec);
         mutex_unlock(&ec->lock);
 }
 
+static void acpi_ec_gpe_query(void *ec_cxt);
+
+static int ec_check_sci(struct acpi_ec *ec, u8 state)
+{
+        if (state & ACPI_EC_FLAG_SCI) {
+                if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
+                        pr_debug(PREFIX "push gpe query to the queue\n");
+                        return acpi_os_execute(OSL_NOTIFY_HANDLER,
+                                acpi_ec_gpe_query, ec);
+                }
+        }
+        return 0;
+}
+
 static u32 acpi_ec_gpe_handler(void *data)
 {
         struct acpi_ec *ec = data;
-        u8 status;
 
         pr_debug(PREFIX "~~~> interrupt\n");
-        status = acpi_ec_read_status(ec);
 
-        advance_transaction(ec, status);
-        if (ec_transaction_done(ec) && (status & ACPI_EC_FLAG_IBF) == 0)
+        advance_transaction(ec, acpi_ec_read_status(ec));
+        if (ec_transaction_done(ec) &&
+            (acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF) == 0) {
                 wake_up(&ec->wait);
-        ec_check_sci(ec, status);
+                ec_check_sci(ec, acpi_ec_read_status(ec));
+        }
         return ACPI_INTERRUPT_HANDLED;
 }