Fix stale EC events on Samsung systems (rhbz 1003602)

2 files changed, 182 insertions, 0 deletions

diff --git a/ACPI-EC-Clear-stale-EC-events-on-Samsung-systems.patch b/ACPI-EC-Clear-stale-EC-events-on-Samsung-systems.patch
new file mode 100644
index 000000000..de1367bfa
--- /dev/null
+++ b/ACPI-EC-Clear-stale-EC-events-on-Samsung-systems.patch
@@ -0,0 +1,175 @@
+Bugzilla: 1003602
+Upstream-status: Queued for 3.15 https://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?id=27095111cbafd3212c7e9a4a8cef1099b7520ca8
+
+From 27095111cbafd3212c7e9a4a8cef1099b7520ca8 Mon Sep 17 00:00:00 2001
+From: Kieran Clancy <clancy.kieran@gmail.com>
+Date: Fri, 28 Feb 2014 14:12:28 +0000
+Subject: ACPI / EC: Clear stale EC events on Samsung systems
+
+A number of Samsung notebooks (530Uxx/535Uxx/540Uxx/550Pxx/900Xxx/etc)
+continue to log events during sleep (lid open/close, AC plug/unplug,
+battery level change), which accumulate in the EC until a buffer fills.
+After the buffer is full (tests suggest it holds 8 events), GPEs stop
+being triggered for new events. This state persists on wake or even on
+power cycle, and prevents new events from being registered until the EC
+is manually polled.
+
+This is the root cause of a number of bugs, including AC not being
+detected properly, lid close not triggering suspend, and low ambient
+light not triggering the keyboard backlight. The bug also seemed to be
+responsible for performance issues on at least one user's machine.
+
+Juan Manuel Cabo found the cause of bug and the workaround of polling
+the EC manually on wake.
+
+The loop which clears the stale events is based on an earlier patch by
+Lan Tianyu (see referenced attachment).
+
+This patch:
+ - Adds a function acpi_ec_clear() which polls the EC for stale _Q
+   events at most ACPI_EC_CLEAR_MAX (currently 100) times. A warning is
+   logged if this limit is reached.
+ - Adds a flag EC_FLAGS_CLEAR_ON_RESUME which is set to 1 if the DMI
+   system vendor is Samsung. This check could be replaced by several
+   more specific DMI vendor/product pairs, but it's likely that the bug
+   affects more Samsung products than just the five series mentioned
+   above. Further, it should not be harmful to run acpi_ec_clear() on
+   systems without the bug; it will return immediately after finding no
+   data waiting.
+ - Runs acpi_ec_clear() on initialisation (boot), from acpi_ec_add()
+ - Runs acpi_ec_clear() on wake, from acpi_ec_unblock_transactions()
+
+References: https://bugzilla.kernel.org/show_bug.cgi?id=44161
+References: https://bugzilla.kernel.org/show_bug.cgi?id=45461
+References: https://bugzilla.kernel.org/show_bug.cgi?id=57271
+References: https://bugzilla.kernel.org/attachment.cgi?id=126801
+Suggested-by: Juan Manuel Cabo <juanmanuel.cabo@gmail.com>
+Signed-off-by: Kieran Clancy <clancy.kieran@gmail.com>
+Reviewed-by: Lan Tianyu <tianyu.lan@intel.com>
+Reviewed-by: Dennis Jansen <dennis.jansen@web.de>
+Tested-by: Kieran Clancy <clancy.kieran@gmail.com>
+Tested-by: Juan Manuel Cabo <juanmanuel.cabo@gmail.com>
+Tested-by: Dennis Jansen <dennis.jansen@web.de>
+Tested-by: Maurizio D'Addona <mauritiusdadd@gmail.com>
+Tested-by: San Zamoyski <san@plusnet.pl>
+Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+---
+diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
+index 959d41a..d7d32c2 100644
+--- a/drivers/acpi/ec.c
++++ b/drivers/acpi/ec.c
+@@ -67,6 +67,8 @@ enum ec_command {
+ #define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
+ #define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */
+ #define ACPI_EC_MSI_UDELAY	550	/* Wait 550us for MSI EC */
++#define ACPI_EC_CLEAR_MAX	100	/* Maximum number of events to query
++					 * when trying to clear the EC */
+ 
+ enum {
+ 	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
+@@ -116,6 +118,7 @@ EXPORT_SYMBOL(first_ec);
+ 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 */
+ 
+ /* --------------------------------------------------------------------------
+                              Transaction Management
+@@ -440,6 +443,29 @@ acpi_handle ec_get_handle(void)
+ 
+ EXPORT_SYMBOL(ec_get_handle);
+ 
++static int acpi_ec_query_unlocked(struct acpi_ec *ec, u8 *data);
++
++/*
++ * Clears stale _Q events that might have accumulated in the EC.
++ * Run with locked ec mutex.
++ */
++static void acpi_ec_clear(struct acpi_ec *ec)
++{
++	int i, status;
++	u8 value = 0;
++
++	for (i = 0; i < ACPI_EC_CLEAR_MAX; i++) {
++		status = acpi_ec_query_unlocked(ec, &value);
++		if (status || !value)
++			break;
++	}
++
++	if (unlikely(i == ACPI_EC_CLEAR_MAX))
++		pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
++	else
++		pr_info("%d stale EC events cleared\n", i);
++}
++
+ void acpi_ec_block_transactions(void)
+ {
+ 	struct acpi_ec *ec = first_ec;
+@@ -463,6 +489,10 @@ void acpi_ec_unblock_transactions(void)
+ 	mutex_lock(&ec->mutex);
+ 	/* Allow transactions to be carried out again */
+ 	clear_bit(EC_FLAGS_BLOCKED, &ec->flags);
++
++	if (EC_FLAGS_CLEAR_ON_RESUME)
++		acpi_ec_clear(ec);
++
+ 	mutex_unlock(&ec->mutex);
+ }
+ 
+@@ -821,6 +851,13 @@ static int acpi_ec_add(struct acpi_device *device)
+ 
+ 	/* EC is fully operational, allow queries */
+ 	clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
++
++	/* Clear stale _Q events if hardware might require that */
++	if (EC_FLAGS_CLEAR_ON_RESUME) {
++		mutex_lock(&ec->mutex);
++		acpi_ec_clear(ec);
++		mutex_unlock(&ec->mutex);
++	}
+ 	return ret;
+ }
+ 
+@@ -922,6 +959,30 @@ static int ec_enlarge_storm_threshold(const struct dmi_system_id *id)
+ 	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)
++ *
++ * https://bugzilla.kernel.org/show_bug.cgi?id=44161
++ *
++ * Ideally, the EC should also be instructed NOT to accumulate events during
++ * sleep (which Windows seems to do somehow), but the interface to control this
++ * behaviour is not known at this time.
++ *
++ * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
++ * however it is very likely that other Samsung models are affected.
++ *
++ * On systems which don't accumulate _Q events during sleep, this extra check
++ * should be harmless.
++ */
++static int ec_clear_on_resume(const struct dmi_system_id *id)
++{
++	pr_debug("Detected system needing EC poll on resume.\n");
++	EC_FLAGS_CLEAR_ON_RESUME = 1;
++	return 0;
++}
++
+ static struct dmi_system_id ec_dmi_table[] __initdata = {
+ 	{
+ 	ec_skip_dsdt_scan, "Compal JFL92", {
+@@ -965,6 +1026,9 @@ static struct dmi_system_id ec_dmi_table[] __initdata = {
+ 	ec_validate_ecdt, "ASUS hardware", {
+ 	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTek Computer Inc."),
+ 	DMI_MATCH(DMI_PRODUCT_NAME, "L4R"),}, NULL},
++	{
++	ec_clear_on_resume, "Samsung hardware", {
++	DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
+ 	{},
+ };
+ 
+--
+cgit v0.9.2
diff --git a/kernel.spec b/kernel.spec
index 86102a6c8..d2443387a 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -652,6 +652,9 @@ Patch25035: Bluetooth-allocate-static-minor-for-vhci.patch
 #Fixes module loading on ppc64le
 Patch25036: ppc64le_module_fix.patch
 
+#rhbz 1003602
+Patch25037: ACPI-EC-Clear-stale-EC-events-on-Samsung-systems.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1311,6 +1314,9 @@ ApplyPatch Bluetooth-allocate-static-minor-for-vhci.patch
 # Fixes module loading on ppc64le
 ApplyPatch ppc64le_module_fix.patch
 
+#rhbz 1003602
+ApplyPatch ACPI-EC-Clear-stale-EC-events-on-Samsung-systems.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2091,6 +2097,7 @@ fi
 #                                    ||     ||
 %changelog
 * Thu Mar 06 2014 Josh Boyer <jwboyer@fedoraproject.org>
+- Fix stale EC events on Samsung systems (rhbz 1003602)
 - Add ppc64le support from Brent Baude (rhbz 1073102)
 - Fix depmod error message from hci_vhci module (rhbz 1051748)
 - Fix bogus WARN in iwlwifi (rhbz 1071998)