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SubjectACPI regression in 2.6.25-rc6 (function keys stop working)

There is an ACPI regression in 2.6.25-rc6, which causes the ACPI keys
to stop working on my laptop, an Asus V6VA. git bisect identified the
appended commit as guilty, and reverting it indeed fixes the problem
for me. Attached are my .config, a good dmesg and a bad one. The diff
between both dmesg reveals this interesting hunk:

@@ -121,8 +121,9 @@
ACPI: (supports S0 S1 S3 S4 S5)
ACPI: Using IOAPIC for interrupt routing
ACPI: EC: non-query interrupt received, switching to interrupt mode
+ACPI: EC: GPE storm detected, disabling EC GPE
ACPI: EC: GPE = 0x1c, I/O: command/status = 0x66, data = 0x62
-ACPI: EC: driver started in interrupt mode
+ACPI: EC: driver started in poll mode
ACPI: PCI Root Bridge [PCI0] (0000:00)
pci 0000:00:1f.0: Enabled ICH6/i801 SMBus device
pci 0000:00:1f.0: quirk: region 0800-087f claimed by ICH6 ACPI/GPIO/TCO


commit 2c81ce4c9c37b910210f2640c28e98a0c398dc26
Author: Alexey Starikovskiy <>
Date: Tue Mar 11 13:30:00 2008 -0400

ACPI: EC: Handle IRQ storm on Acer laptops

On some Acer systems, the HW fails to clear the GPE source,
causing an interrupt storm.

So in EC interrupt mode, we count how many interrupts we
receive when waiting. If we get more than 5, we give
up on interrupt mode and revert to polling mode.

Also, for polling mode to work on Acers, we need
to insert a delay.

Signed-off-by: Alexey Starikovskiy <>
Signed-off-by: Len Brown <>

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index caf873c..2c77359 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -129,6 +129,7 @@ static struct acpi_ec {
struct mutex lock;
wait_queue_head_t wait;
struct list_head list;
+ atomic_t irq_count;
u8 handlers_installed;
} *boot_ec, *first_ec;

@@ -181,6 +182,8 @@ static int acpi_ec_wait(struct acpi_ec *ec, enum
ec_event event, int force_poll)
int ret = 0;

+ atomic_set(&ec->irq_count, 0);
if (unlikely(event == ACPI_EC_EVENT_OBF_1 &&
test_bit(EC_FLAGS_NO_OBF1_GPE, &ec->flags)))
force_poll = 1;
@@ -227,6 +230,7 @@ static int acpi_ec_wait(struct acpi_ec *ec, enum
ec_event event, int force_poll)
while (time_before(jiffies, delay)) {
if (acpi_ec_check_status(ec, event))
goto end;
+ msleep(5);
pr_err(PREFIX "acpi_ec_wait timeout,"
@@ -529,6 +533,13 @@ static u32 acpi_ec_gpe_handler(void *data)
struct acpi_ec *ec = data;

pr_debug(PREFIX "~~~> interrupt\n");
+ atomic_inc(&ec->irq_count);
+ if (atomic_read(&ec->irq_count) > 5) {
+ pr_err(PREFIX "GPE storm detected, disabling EC GPE\n");
+ acpi_disable_gpe(NULL, ec->gpe, ACPI_ISR);
+ clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
+ }
clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags))

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