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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: Venkat Raghavulu <venkat.raghavulu@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@ -71,6 +71,7 @@ enum ec_command {
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#define ACPI_EC_DELAY 500 /* Wait 500ms max. during EC ops */
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#define ACPI_EC_UDELAY_GLK 1000 /* Wait 1ms max. to get global lock */
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#define ACPI_EC_MSI_UDELAY 550 /* Wait 550us for MSI EC */
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#define ACPI_EC_UDELAY_POLL 1000 /* Wait 1ms for EC transaction polling */
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#define ACPI_EC_CLEAR_MAX 100 /* Maximum number of events to query
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* when trying to clear the EC */
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@ -118,6 +119,7 @@ struct transaction {
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u8 wlen;
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u8 rlen;
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u8 flags;
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unsigned long timestamp;
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};
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static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
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@ -155,6 +157,7 @@ static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
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{
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u8 x = inb(ec->data_addr);
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ec->curr->timestamp = jiffies;
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pr_debug("EC_DATA(R) = 0x%2.2x\n", x);
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return x;
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}
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@ -163,12 +166,14 @@ static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
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{
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pr_debug("EC_SC(W) = 0x%2.2x\n", command);
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outb(command, ec->command_addr);
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ec->curr->timestamp = jiffies;
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}
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static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
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{
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pr_debug("EC_DATA(W) = 0x%2.2x\n", data);
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outb(data, ec->data_addr);
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ec->curr->timestamp = jiffies;
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}
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#ifdef DEBUG
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@ -359,6 +364,7 @@ static void start_transaction(struct acpi_ec *ec)
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{
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ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
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ec->curr->flags = 0;
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ec->curr->timestamp = jiffies;
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advance_transaction(ec);
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}
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@ -370,20 +376,25 @@ static int ec_poll(struct acpi_ec *ec)
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while (repeat--) {
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unsigned long delay = jiffies +
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msecs_to_jiffies(ec_delay);
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unsigned long usecs = ACPI_EC_UDELAY_POLL;
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do {
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/* don't sleep with disabled interrupts */
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if (EC_FLAGS_MSI || irqs_disabled()) {
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udelay(ACPI_EC_MSI_UDELAY);
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usecs = ACPI_EC_MSI_UDELAY;
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udelay(usecs);
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if (ec_transaction_completed(ec))
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return 0;
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} else {
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if (wait_event_timeout(ec->wait,
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ec_transaction_completed(ec),
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msecs_to_jiffies(1)))
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usecs_to_jiffies(usecs)))
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return 0;
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}
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spin_lock_irqsave(&ec->lock, flags);
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advance_transaction(ec);
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if (time_after(jiffies,
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ec->curr->timestamp +
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usecs_to_jiffies(usecs)))
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advance_transaction(ec);
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spin_unlock_irqrestore(&ec->lock, flags);
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} while (time_before(jiffies, delay));
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pr_debug("controller reset, restart transaction\n");
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