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 <[email protected]> Signed-off-by: Lv Zheng <[email protected]> --- drivers/acpi/ec.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 2540870..e000cf7 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -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); } @@ -370,20 +376,25 @@ 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); - advance_transaction(ec); + 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)); pr_debug("controller reset, restart transaction\n"); -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
