tty_audit_push(tty);
}
return eof_push ? -EAGAIN : 0;
+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
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