From: Lv Zheng <lv.zheng@xxxxxxxxx> After we've added the first command byte write into advance_transaction(), the IBF=0 waiter is duplicated with the command completion waiter implemented in the ec_poll() because: If IBF=1 blocked the first command byte write invoked in the task context ec_poll(), it would be kicked off upon IBF=0 interrupt or timed out and retried again in the task context. This patch removes this seperate and duplicate IBF=0 waiter, by doing so, we can reduce the overall number of times to access the EC_SC(R) status register. Reference: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx> Reported-and-tested-by: Gareth Williams <gareth@xxxxxxxxxxxxxxxxxxxx> Tested-by: Steffen Weber <steffen.weber@xxxxxxxxx> [zetalog: first affected by:] Cc: <stable@xxxxxxxxxxxxxxx> # 2.6.11: 7c6db4e0: ACPI: EC: do transaction from interrupt context [zetalog: cleanly applying to:] Cc: <stable@xxxxxxxxxxxxxxx> # 3.14.x: 42b946bb: ACPI / EC: disable GPE before removing GPE handler --- drivers/acpi/ec.c | 27 +-------------------------- 1 file changed, 1 insertion(+), 26 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index f09386e..d016ea3 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -281,23 +281,6 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, return ret; } -static int ec_check_ibf0(struct acpi_ec *ec) -{ - u8 status = acpi_ec_read_status(ec); - return (status & ACPI_EC_FLAG_IBF) == 0; -} - -static int ec_wait_ibf0(struct acpi_ec *ec) -{ - 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), - msecs_to_jiffies(1))) - return 0; - return -ETIME; -} - static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t) { int status; @@ -318,12 +301,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t) goto unlock; } } - if (ec_wait_ibf0(ec)) { - pr_err("input buffer is not empty, " - "aborting transaction\n"); - status = -ETIME; - goto end; - } pr_debug("transaction start (cmd=0x%02x, addr=0x%02x)\n", t->command, t->wdata ? t->wdata[0] : 0); /* disable GPE during transaction if storm is detected */ @@ -347,7 +324,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t) set_bit(EC_FLAGS_GPE_STORM, &ec->flags); } pr_debug("transaction end\n"); -end: if (ec->global_lock) acpi_release_global_lock(glk); unlock: @@ -653,8 +629,7 @@ static u32 acpi_ec_gpe_handler(acpi_handle gpe_device, spin_lock_irqsave(&ec->lock, flags); advance_transaction(ec); spin_unlock_irqrestore(&ec->lock, flags); - if (ec_transaction_completed(ec) && - (acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF) == 0) { + if (ec_transaction_completed(ec)) { wake_up(&ec->wait); ec_check_sci(ec, acpi_ec_read_status(ec)); } -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
