Patch "ACPI / EC: Remove duplicated ec_wait_ibf0() waiter" has been added to the 3.15-stable tree

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This is a note to let you know that I've just added the patch titled

    ACPI / EC: Remove duplicated ec_wait_ibf0() waiter

to the 3.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     acpi-ec-remove-duplicated-ec_wait_ibf0-waiter.patch
and it can be found in the queue-3.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 9b80f0f73ae1583c22325ede341c74195847618c Mon Sep 17 00:00:00 2001
From: Lv Zheng <lv.zheng@xxxxxxxxx>
Date: Sun, 15 Jun 2014 08:41:48 +0800
Subject: ACPI / EC: Remove duplicated ec_wait_ibf0() waiter

From: Lv Zheng <lv.zheng@xxxxxxxxx>

commit 9b80f0f73ae1583c22325ede341c74195847618c upstream.

After we've added the first command byte write into advance_transaction(),
the IBF=0 waiter is duplicated with the command completion waiter
implemented in the ec_poll() because:
   If IBF=1 blocked the first command byte write invoked in the task
   context ec_poll(), it would be kicked off upon IBF=0 interrupt or timed
   out and retried again in the task context.

Remove this seperate and duplicate IBF=0 waiter.  By doing so we can
reduce the overall number of times to access the EC_SC(R) status
register.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891
Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931
Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911
Reported-and-tested-by: Gareth Williams <gareth@xxxxxxxxxxxxxxxxxxxx>
Reported-and-tested-by: Hans de Goede <jwrdegoede@xxxxxxxxxxxxxxxxx>
Reported-by: Barton Xu <tank.xuhan@xxxxxxxxx>
Tested-by: Steffen Weber <steffen.weber@xxxxxxxxx>
Tested-by: Arthur Chen <axchen@xxxxxxxxxx>
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/acpi/ec.c |   27 +--------------------------
 1 file changed, 1 insertion(+), 26 deletions(-)

--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -281,23 +281,6 @@ static int acpi_ec_transaction_unlocked(
 	return ret;
 }
 
-static int ec_check_ibf0(struct acpi_ec *ec)
-{
-	u8 status = acpi_ec_read_status(ec);
-	return (status & ACPI_EC_FLAG_IBF) == 0;
-}
-
-static int ec_wait_ibf0(struct acpi_ec *ec)
-{
-	unsigned long delay = jiffies + msecs_to_jiffies(ec_delay);
-	/* interrupt wait manually if GPE mode is not active */
-	while (time_before(jiffies, delay))
-		if (wait_event_timeout(ec->wait, ec_check_ibf0(ec),
-					msecs_to_jiffies(1)))
-			return 0;
-	return -ETIME;
-}
-
 static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
 {
 	int status;
@@ -318,12 +301,6 @@ static int acpi_ec_transaction(struct ac
 			goto unlock;
 		}
 	}
-	if (ec_wait_ibf0(ec)) {
-		pr_err("input buffer is not empty, "
-				"aborting transaction\n");
-		status = -ETIME;
-		goto end;
-	}
 	pr_debug("transaction start (cmd=0x%02x, addr=0x%02x)\n",
 			t->command, t->wdata ? t->wdata[0] : 0);
 	/* disable GPE during transaction if storm is detected */
@@ -347,7 +324,6 @@ static int acpi_ec_transaction(struct ac
 		set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
 	}
 	pr_debug("transaction end\n");
-end:
 	if (ec->global_lock)
 		acpi_release_global_lock(glk);
 unlock:
@@ -653,8 +629,7 @@ static u32 acpi_ec_gpe_handler(acpi_hand
 	spin_lock_irqsave(&ec->lock, flags);
 	advance_transaction(ec);
 	spin_unlock_irqrestore(&ec->lock, flags);
-	if (ec_transaction_completed(ec) &&
-	    (acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF) == 0) {
+	if (ec_transaction_completed(ec)) {
 		wake_up(&ec->wait);
 		ec_check_sci(ec, acpi_ec_read_status(ec));
 	}


Patches currently in stable-queue which might be from lv.zheng@xxxxxxxxx are

queue-3.15/acpi-ec-avoid-race-condition-related-to-advance_transaction.patch
queue-3.15/acpi-ec-fix-race-condition-in-ec_transaction_completed.patch
queue-3.15/acpi-ec-add-asynchronous-command-byte-write-support.patch
queue-3.15/acpi-ec-remove-duplicated-ec_wait_ibf0-waiter.patch
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