[PATCH] ACPI: EC: restart failed command

[Alexey Starikovskiy <astarikovskiy@suse.de>]

Restart current transaction if we recieved unexpected GPEs instead
of needed ones.

Referencies: http://bugzilla.kernel.org/show_bug.cgi?id=11896
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
---

 drivers/acpi/ec.c |   41 +++++++++++++++++++++++++++++------------
 1 files changed, 29 insertions(+), 12 deletions(-)


diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index db7d67e..87337b0 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -100,6 +100,8 @@ struct transaction {
 	u8 *rdata;
 	unsigned short irq_count;
 	u8 command;
+	u8 wi;
+	u8 ri;
 	u8 wlen;
 	u8 rlen;
 	bool done;
@@ -185,26 +187,34 @@ static int ec_transaction_done(struct acpi_ec *ec)
 	return ret;
 }
 
+static void start_transaction(struct acpi_ec *ec)
+{
+	ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
+	ec->curr->done = false;
+	acpi_ec_write_cmd(ec, ec->curr->command);
+}
+
 static void gpe_transaction(struct acpi_ec *ec, u8 status)
 {
 	unsigned long flags;
 	spin_lock_irqsave(&ec->curr_lock, flags);
 	if (!ec->curr)
 		goto unlock;
-	if (ec->curr->wlen > 0) {
-		if ((status & ACPI_EC_FLAG_IBF) == 0) {
-			acpi_ec_write_data(ec, *(ec->curr->wdata++));
-			--ec->curr->wlen;
-		} else
+	if (ec->curr->wlen > ec->curr->wi) {
+		if ((status & ACPI_EC_FLAG_IBF) == 0)
+			acpi_ec_write_data(ec,
+				ec->curr->wdata[ec->curr->wi++]);
+		else
 			goto err;
-	} else if (ec->curr->rlen > 0) {
+	} else if (ec->curr->rlen > ec->curr->ri) {
 		if ((status & ACPI_EC_FLAG_OBF) == 1) {
-			*(ec->curr->rdata++) = acpi_ec_read_data(ec);
-			if (--ec->curr->rlen == 0)
+			ec->curr->rdata[ec->curr->ri++] = acpi_ec_read_data(ec);
+			if (ec->curr->rlen == ec->curr->ri)
 				ec->curr->done = true;
 		} else
 			goto err;
-	} else if (ec->curr->wlen == 0 && (status & ACPI_EC_FLAG_IBF) == 0)
+	} else if (ec->curr->wlen == ec->curr->wi &&
+		   (status & ACPI_EC_FLAG_IBF) == 0)
 		ec->curr->done = true;
 	goto unlock;
 err:
@@ -219,6 +229,15 @@ static int acpi_ec_wait(struct acpi_ec *ec)
 	if (wait_event_timeout(ec->wait, ec_transaction_done(ec),
 			       msecs_to_jiffies(ACPI_EC_DELAY)))
 		return 0;
+	/* try restart command if we get any false interrupts */
+	if (ec->curr->irq_count &&
+	    (acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF) == 0) {
+		pr_debug(PREFIX "controller reset, restart transaction\n");
+		start_transaction(ec);
+		if (wait_event_timeout(ec->wait, ec_transaction_done(ec),
+					msecs_to_jiffies(ACPI_EC_DELAY)))
+			return 0;
+	}
 	/* missing GPEs, switch back to poll mode */
 	if (printk_ratelimit())
 		pr_info(PREFIX "missing confirmations, "
@@ -268,10 +287,8 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
 	/* start transaction */
 	spin_lock_irqsave(&ec->curr_lock, tmp);
 	/* following two actions should be kept atomic */
-	t->irq_count = 0;
-	t->done = false;
 	ec->curr = t;
-	acpi_ec_write_cmd(ec, ec->curr->command);
+	start_transaction(ec);
 	if (ec->curr->command == ACPI_EC_COMMAND_QUERY)
 		clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
 	spin_unlock_irqrestore(&ec->curr_lock, tmp);