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SubjectRe: acpi-test tree on eeepc: EC error message on second resume
Alan Jenkins wrote:
> Rafael J. Wysocki wrote:
>> On Saturday, 11 of October 2008, Alexey Starikovskiy wrote:
>>
>>> Rafael J. Wysocki wrote:
>>>
>>>>> No, we discussed this before -- we are outside of the transaction, thus
>>>>> no GPE
>>>>> activity could interfere with ec_check_ibf0.
>>>>>
>>>> Ok, this is in the process context and we don't really expect to get an
>>>> interrupt at this point, but what happens if the EC generates an event that's
>>>> not related to any transiaction. Is that guaranteed to never happen?
>>>>
>>> Interrupt handler in this case can't cause a change to status register, thus our
>>> read of it will not be affected by interrupt.
>>>
>> Ok, thanks.
>>
>> Alan, does the patch work for you?
>>
>> Rafael
>>
>
> Yes. Two reboot cycles, three suspend/resume cycles each, and no error
> message.
>
> I hope we have a better fix in mind though :-P. The patch doesn't solve
> the unnecessary 500ms delay when this thing happens.

Something like this?

Regards,
Alex.
ACPI: EC: Check for IBF=0 once again after timeout

From: Alexey Starikovskiy <astarikovskiy@suse.de>

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
---
drivers/acpi/ec.c | 14 ++++++++++++--
1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 69f5f78..5e7c9c5 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -300,6 +300,17 @@ static int ec_check_ibf0(struct acpi_ec *ec)
return (status & ACPI_EC_FLAG_IBF) == 0;
}

+static int ec_wait_ibf0(struct acpi_ec *ec)
+{
+ unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
+ 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 force_poll)
{
@@ -317,8 +328,7 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t,
goto unlock;
}
}
- if (!wait_event_timeout(ec->wait, ec_check_ibf0(ec),
- msecs_to_jiffies(ACPI_EC_DELAY))) {
+ if (ec_wait_ibf0(ec)) {
pr_err(PREFIX "input buffer is not empty, "
"aborting transaction\n");
status = -ETIME;
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