[3.13.y.z extended stable] Patch "ACPI / EC: Fix regression due to conflicting firmware behavior between Samsung and Acer." has been added to staging queue

[Kamal Mostafa]

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

    ACPI / EC: Fix regression due to conflicting firmware behavior between Samsung and Acer.

to the linux-3.13.y-queue branch of the 3.13.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-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.11.

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

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 0e6b9f3eac8eafdac09ad1103b168d968a13c159 Mon Sep 17 00:00:00 2001
From: Lv Zheng <lv.zheng at intel.com>
Date: Wed, 29 Oct 2014 11:33:49 +0800
Subject: ACPI / EC: Fix regression due to conflicting firmware behavior
 between Samsung and Acer.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 79149001105f18bd2285ada109f9229ea24a7571 upstream.

It is reported that Samsung laptops that need to poll events are broken by
the following commit:
 Commit 3afcf2ece453e1a8c2c6de19cdf06da3772a1b08
 Subject: ACPI / EC: Add support to disallow QR_EC to be issued when SCI_EVT isn't set

The behaviors of the 2 vendor firmwares are conflict:
 1. Acer: OSPM shouldn't issue QR_EC unless SCI_EVT is set, firmware
         automatically sets SCI_EVT as long as there is event queued up.
 2. Samsung: OSPM should issue QR_EC whatever SCI_EVT is set, firmware
            returns 0 when there is no event queued up.

This patch is a quick fix to distinguish the behaviors to make Acer
behavior only effective for Acer EC firmware so that the breakages on
Samsung EC firmware can be avoided.

Fixes: 3afcf2ece453 (ACPI / EC: Add support to disallow QR_EC to be issued ...)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-and-tested-by: Ortwin Glück <odi at odi.ch>
Signed-off-by: Lv Zheng <lv.zheng at intel.com>
[ rjw : Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>

Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/acpi/ec.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index aa232a3..8c02f84 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -127,6 +127,7 @@ static int EC_FLAGS_MSI; /* Out-of-spec MSI controller */
 static int EC_FLAGS_VALIDATE_ECDT; /* ASUStec ECDTs need to be validated */
 static int EC_FLAGS_SKIP_DSDT_SCAN; /* Not all BIOS survive early DSDT scan */
 static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
+static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */

 /* --------------------------------------------------------------------------
                              Transaction Management
@@ -204,13 +205,8 @@ static bool advance_transaction(struct acpi_ec *ec)
 		}
 		return wakeup;
 	} else {
-		/*
-		 * There is firmware refusing to respond QR_EC when SCI_EVT
-		 * is not set, for which case, we complete the QR_EC
-		 * without issuing it to the firmware.
-		 * https://bugzilla.kernel.org/show_bug.cgi?id=86211
-		 */
-		if (!(status & ACPI_EC_FLAG_SCI) &&
+		if (EC_FLAGS_QUERY_HANDSHAKE &&
+		    !(status & ACPI_EC_FLAG_SCI) &&
 		    (t->command == ACPI_EC_COMMAND_QUERY)) {
 			t->flags |= ACPI_EC_COMMAND_POLL;
 			t->rdata[t->ri++] = 0x00;
@@ -996,6 +992,18 @@ static int ec_enlarge_storm_threshold(const struct dmi_system_id *id)
 }

 /*
+ * Acer EC firmware refuses to respond QR_EC when SCI_EVT is not set, for
+ * which case, we complete the QR_EC without issuing it to the firmware.
+ * https://bugzilla.kernel.org/show_bug.cgi?id=86211
+ */
+static int ec_flag_query_handshake(const struct dmi_system_id *id)
+{
+	pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
+	EC_FLAGS_QUERY_HANDSHAKE = 1;
+	return 0;
+}
+
+/*
  * On some hardware it is necessary to clear events accumulated by the EC during
  * sleep. These ECs stop reporting GPEs until they are manually polled, if too
  * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
@@ -1065,6 +1073,9 @@ static struct dmi_system_id ec_dmi_table[] __initdata = {
 	{
 	ec_clear_on_resume, "Samsung hardware", {
 	DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
+	{
+	ec_flag_query_handshake, "Acer hardware", {
+	DMI_MATCH(DMI_SYS_VENDOR, "Acer"), }, NULL},
 	{},
 };

--
1.9.1