[3.11.y.z extended stable] Patch "ACPI / EC: Remove duplicated ec_wait_ibf0() waiter" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ACPI / EC: Remove duplicated ec_wait_ibf0() waiter

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From f4ff3f1754447b63625a3123b5f0707866da060b Mon Sep 17 00:00:00 2001
From: Lv Zheng <lv.zheng at intel.com>
Date: Sun, 15 Jun 2014 08:41:48 +0800
Subject: [PATCH 20/41] ACPI / EC: Remove duplicated ec_wait_ibf0() waiter

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 at garethwilliams.me.uk>
Reported-and-tested-by: Hans de Goede <jwrdegoede at fedoraproject.org>
Reported-by: Barton Xu <tank.xuhan at gmail.com>
Tested-by: Steffen Weber <steffen.weber at gmail.com>
Tested-by: Arthur Chen <axchen at nvidia.com>
Signed-off-by: Lv Zheng <lv.zheng at intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
[ luis: backported to 3.11: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/acpi/ec.c | 27 +--------------------------
 1 file changed, 1 insertion(+), 26 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 02090c6095fe..59bf2d016fd1 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -288,23 +288,6 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
 	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;
@@ -325,12 +308,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
 			goto unlock;
 		}
 	}
-	if (ec_wait_ibf0(ec)) {
-		pr_err(PREFIX "input buffer is not empty, "
-				"aborting transaction\n");
-		status = -ETIME;
-		goto end;
-	}
 	pr_debug(PREFIX "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 */
@@ -354,7 +331,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
 		set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
 	}
 	pr_debug(PREFIX "transaction end\n");
-end:
 	if (ec->global_lock)
 		acpi_release_global_lock(glk);
 unlock:
@@ -680,8 +656,7 @@ static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
 	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));
 	}
--
1.9.1