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Subject[PATCH 3/7] ACPI/EC: Remove duplicated ec_wait_ibf0() waiter.
Date
After we've added 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.

Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=70891
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Reported-and-tested-by: Gareth Williams <gareth@garethwilliams.me.uk>
Tested-by: Steffen Weber <steffen.weber@gmail.com>
[zetalog: first affected by:]
Cc: <stable@vger.kernel.org> # 2.6.11: 7c6db4e0: ACPI: EC: do transaction from interrupt context
[zetalog: cleanly applying to:]
Cc: <stable@vger.kernel.org> # 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


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