[FIX PATCH] ACPI/EC: Restart transaction even when IBF flag setting

[Lan Tianyu <tianyu.lan@intel.com>]

Some time, EC works abnormally with IBF flag always setting.
IBF means "The host has written a byte of data to the command
or data port, but the embedded controller has not yet read it".
This will cause all EC requests to be failed with timeout error.

After several trials, find restarting transaction with IBF flag
setting can make EC work again. This patch is to remove the
IBF flag check before restarting transaction and increase the
repeat number to 5. Some time, once restart is not enough.

This bug happens on the different machines. (e.g Asus V1S,
Dell Latitude E6530, Samsung R719, Acer Aspire 5930G,
Sony Vaio SR19VN and so on).

Related bugs:
	https://bugzilla.kernel.org/show_bug.cgi?id=14733
	https://bugzilla.kernel.org/show_bug.cgi?id=15560
	https://bugzilla.kernel.org/show_bug.cgi?id=15946
	https://bugzilla.kernel.org/show_bug.cgi?id=42945
	https://bugzilla.kernel.org/show_bug.cgi?id=48221

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
---
 drivers/acpi/ec.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index d45b287..edc0081 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -223,7 +223,7 @@ static int ec_check_sci_sync(struct acpi_ec *ec, u8 state)
 static int ec_poll(struct acpi_ec *ec)
 {
 	unsigned long flags;
-	int repeat = 2; /* number of command restarts */
+	int repeat = 5; /* number of command restarts */
 	while (repeat--) {
 		unsigned long delay = jiffies +
 			msecs_to_jiffies(ec_delay);
@@ -241,8 +241,6 @@ static int ec_poll(struct acpi_ec *ec)
 			}
 			advance_transaction(ec, acpi_ec_read_status(ec));
 		} while (time_before(jiffies, delay));
-		if (acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF)
-			break;
 		pr_debug(PREFIX "controller reset, restart transaction\n");
 		spin_lock_irqsave(&ec->lock, flags);
 		start_transaction(ec);
-- 
1.7.9.5