Commit 7a18e96d authored Oct 21, 2010 by Thomas Renninger Committed by Len Brown Oct 22, 2010

ACPI: Make Embedded Controller command timeout delay configurable



Here and then there show up machines which need higher timeout values.
Finding this on affected machines can be cumbersome, because
ACPI_EC_DELAY is a compile option -> make it configurable via boot param.

This can even be provided writable at runtime via:
/sys/modules/acpi/parameters/ec_delay

Known machines where this helps:
Some HP machines where for whatever reasons specific EC accesses take
very long at resume from S3 (in _WAK function).
The AE_TIME error is passed upwards and the ACPI interpreter will
not execute the rest of the _WAK function which results in not properly
initialized devices/variables with different side-effects.

Afaik, on some MSI machines this helped as well.

If this param is needed there probably are underlying problems like:
  - EC firmware bug
  - A kernel EC driver bug
  - An ACPI interpreter behavior (e.g. timings when specific
    EC accesses happen and how) which the EC does not like
  - ...
which should get evaluated further, but often are nasty or
impossible to fix from OS side.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

parent f6f94e2a

drivers/acpi/ec.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -83,6 +83,11 @@ enum {
		EC_FLAGS_BLOCKED, /* Transactions are blocked */
		};

		/* ec.c is compiled in acpi namespace so this shows up as acpi.ec_delay param */
		static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY;
		module_param(ec_delay, uint, 0644);
		MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes");

		/* If we find an EC via the ECDT, we need to keep a ptr to its context */
		/* External interfaces use first EC only, so remember */
		typedef int (acpi_ec_query_func) (void data);
		@@ -210,7 +215,7 @@ static int ec_poll(struct acpi_ec *ec)
		int repeat = 2; /* number of command restarts */
		while (repeat--) {
		unsigned long delay = jiffies +
		msecs_to_jiffies(ACPI_EC_DELAY);
		msecs_to_jiffies(ec_delay);
		do {
		/* don't sleep with disabled interrupts */
		if (EC_FLAGS_MSI \|\| irqs_disabled()) {
		@@ -265,7 +270,7 @@ static int ec_check_ibf0(struct acpi_ec *ec)

		static int ec_wait_ibf0(struct acpi_ec *ec)
		{
		unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
		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),

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