Commit 9e295ac1 authored by Lv Zheng's avatar Lv Zheng Committed by Rafael J. Wysocki
Browse files

ACPI / EC: Reduce ec_poll() by referencing the last register access timestamp. 



Timeout in the ec_poll() doesn't refer to the last register access time. It
thus can win the competition against the acpi_ec_gpe_handler() if a
transaction takes longer than 1ms but individual register accesses are less
than 1ms.  In some cases, it can make the following silicon bug easier to
be triggered:
 GPE EN is not wired to the GPE trigger line, so when GPE STS is already
 set when 1 is written to GPE EN, no GPE can be triggered.

This patch adds register access timestamp reference support for ec_poll()
to reduce the number of ec_poll() invocations.

Reported-by: default avatarVenkat Raghavulu <venkat.raghavulu@intel.com>
Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent ca37bfdf

drivers/acpi/ec.c

+14 −3
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ 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_UDELAY_POLL	1000	/* Wait 1ms for EC transaction polling */

#define ACPI_EC_CLEAR_MAX	100	/* Maximum number of events to query

					 * when trying to clear the EC */
@@ -118,6 +119,7 @@ struct transaction { 
	u8 wlen;

	u8 rlen;

	u8 flags;

	unsigned long timestamp;

};



static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
@@ -155,6 +157,7 @@ static inline u8 acpi_ec_read_data(struct acpi_ec *ec) 
{

	u8 x = inb(ec->data_addr);



	ec->curr->timestamp = jiffies;

	pr_debug("EC_DATA(R) = 0x%2.2x\n", x);

	return x;

}
@@ -163,12 +166,14 @@ static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command) 
{

	pr_debug("EC_SC(W) = 0x%2.2x\n", command);

	outb(command, ec->command_addr);

	ec->curr->timestamp = jiffies;

}



static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)

{

	pr_debug("EC_DATA(W) = 0x%2.2x\n", data);

	outb(data, ec->data_addr);

	ec->curr->timestamp = jiffies;

}



#ifdef DEBUG
@@ -359,6 +364,7 @@ static void start_transaction(struct acpi_ec *ec) 
{

	ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;

	ec->curr->flags = 0;

	ec->curr->timestamp = jiffies;

	advance_transaction(ec);

}
@@ -370,19 +376,24 @@ static int ec_poll(struct acpi_ec *ec) 
	while (repeat--) {

		unsigned long delay = jiffies +

			msecs_to_jiffies(ec_delay);

		unsigned long usecs = ACPI_EC_UDELAY_POLL;

		do {

			/* don't sleep with disabled interrupts */

			if (EC_FLAGS_MSI || irqs_disabled()) {

				udelay(ACPI_EC_MSI_UDELAY);

				usecs = ACPI_EC_MSI_UDELAY;

				udelay(usecs);

				if (ec_transaction_completed(ec))

					return 0;

			} else {

				if (wait_event_timeout(ec->wait,

						ec_transaction_completed(ec),

						msecs_to_jiffies(1)))

						usecs_to_jiffies(usecs)))

					return 0;

			}

			spin_lock_irqsave(&ec->lock, flags);

			if (time_after(jiffies,

					ec->curr->timestamp +

					usecs_to_jiffies(usecs)))

				advance_transaction(ec);

			spin_unlock_irqrestore(&ec->lock, flags);

		} while (time_before(jiffies, delay));

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