ACPI / EC: Remove duplicated ec_wait_ibf0() waiter

commit 9b80f0f73ae1583c22325ede341c74195847618c upstream.

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.

Remove 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.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891
Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931
Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911
Reported-and-tested-by: Gareth Williams <gareth@garethwilliams.me.uk>
Reported-and-tested-by: Hans de Goede <jwrdegoede@fedoraproject.org>
Reported-by: Barton Xu <tank.xuhan@gmail.com>
Tested-by: Steffen Weber <steffen.weber@gmail.com>
Tested-by: Arthur Chen <axchen@nvidia.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 4361027..38c9ce3 100644 (file)
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -288,23 +288,6 @@ 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;
@@ -325,12 +308,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
                        goto unlock;
                }
        }
-       if (ec_wait_ibf0(ec)) {
-               pr_err(PREFIX "input buffer is not empty, "
-                               "aborting transaction\n");
-               status = -ETIME;
-               goto end;
-       }
        pr_debug(PREFIX "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 */
@@ -354,7 +331,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
                set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
        }
        pr_debug(PREFIX "transaction end\n");
-end:
        if (ec->global_lock)
                acpi_release_global_lock(glk);
 unlock:
@@ -670,8 +646,7 @@ static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
        spin_lock_irqsave(&ec->curr_lock, flags);
        advance_transaction(ec);
        spin_unlock_irqrestore(&ec->curr_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));
        }