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Date: Thu, 27 Feb 2014 00:31:02 -0300
From: Juan Manuel Cabo <juanmanuel.cabo@...il.com>
To: Li Guang <lig.fnst@...fujitsu.com>
CC: Kieran Clancy <clancy.kieran@...il.com>,
Len Brown <lenb@...nel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
Lan Tianyu <tianyu.lan@...el.com>,
Dennis Jansen <dennis.jansen@....de>
Subject: Re: [PATCH] ACPI / EC: Clear stale EC events on Samsung systems
On 02/27/2014 12:14 AM, Li Guang wrote:
> oh, sorry, I'm referring internal EC firmware code
> for Q event queuing, not ACPI SPEC, ;-)
> for machine you tested, 8 is the queue size,
> but for some unknown also nasty EC firmwares(let's suppose it exists),
> it may queue more Q events.
> and I saw several firmwares queued 32 events by default,
> then, let's say, they be used for some samsung products,
> and also they also forgot to deal with sleep/resume state,
> then, we'll also leave stale Q event there.
>
> Thanks!
>
We tested each on our different samsung models (intel, amd), and it
was 8 across. But you're right, there might be more in the future.
I even saw a bug report in ubuntu's launchpad of an HP with a similar
sounding problem, ( https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.20/+bug/89860 )
which I have no idea if it was caused by the same issue, but if in the future,
the flag ec_clear_on_resume is used to match other DMI's, it might
be a good idea to make the max iteration count bigger.
The only reason that there is a max iteration count, was to prevent
an unexpected case in which an unknown EC never returns 0 after
queue emptied. So far it hasn't been the case. Can we count on it?.
The loop currently does finish early when there are no more events.
I guess changing it 255 or 1000 would be enough, right?
Cheers!
--
Juan Manuel Cabo<juanmanuel.cabo@...il.com>
>> For us, a query is just: send 0x84 through EC CMD port, and read status
>> from CMD port and event type from EC DATA port. This is done with
>> the usual ec.c functions that would handle a query after a GPE interrupt,
>> but using them instead to poll (not GPE initiated) at awake. The EC would
>> then return status without 0x20 mask and 'event type'==0 when no more left.
>>
>> --
>> Juan Manuel Cabo<juanmanuel.cabo@...il.com>
>>
>>
>>
>>
>>>> enum {
>>>> EC_FLAGS_QUERY_PENDING, /* Query is pending */
>>>> @@ -116,6 +118,7 @@ EXPORT_SYMBOL(first_ec);
>>>> static int EC_FLAGS_MSI; /* Out-of-spec MSI controller */
>>>> static int EC_FLAGS_VALIDATE_ECDT; /* ASUStec ECDTs need to be validated */
>>>> static int EC_FLAGS_SKIP_DSDT_SCAN; /* Not all BIOS survive early DSDT scan */
>>>> +static int EC_FLAGS_CLEAR_ON_RESUME; /* EC should be polled on boot/resume */
>>>>
>>>>
>>> seems name is implicit, what about EC_FLAGS_QEVENT_CLR_ON_RESUME?
>>> seems too long :-)
>>>
>>>
>>>> /* --------------------------------------------------------------------------
>>>> Transaction Management
>>>> @@ -440,6 +443,26 @@ acpi_handle ec_get_handle(void)
>>>>
>>>> EXPORT_SYMBOL(ec_get_handle);
>>>>
>>>> +static int acpi_ec_query_unlocked(struct acpi_ec *ec, u8 *data);
>>>> +
>>>> +/* run with locked ec mutex */
>>>> +static void acpi_ec_clear(struct acpi_ec *ec)
>>>> +{
>>>> + int i, status;
>>>> + u8 value = 0;
>>>> +
>>>> + for (i = 0; i< ACPI_EC_CLEAR_MAX; i++) {
>>>> + status = acpi_ec_query_unlocked(ec,&value);
>>>> + if (status || !value)
>>>> + break;
>>>> + }
>>>> +
>>>> + if (i == ACPI_EC_CLEAR_MAX)
>>>> + pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
>>>> + else
>>>> + pr_info("%d stale EC events cleared\n", i);
>>>> +}
>>>> +
>>>> void acpi_ec_block_transactions(void)
>>>> {
>>>> struct acpi_ec *ec = first_ec;
>>>> @@ -463,6 +486,10 @@ void acpi_ec_unblock_transactions(void)
>>>> mutex_lock(&ec->mutex);
>>>> /* Allow transactions to be carried out again */
>>>> clear_bit(EC_FLAGS_BLOCKED,&ec->flags);
>>>> +
>>>> + if (EC_FLAGS_CLEAR_ON_RESUME)
>>>> + acpi_ec_clear(ec);
>>>> +
>>>> mutex_unlock(&ec->mutex);
>>>> }
>>>>
>>>> @@ -821,6 +848,13 @@ static int acpi_ec_add(struct acpi_device *device)
>>>>
>>>> /* EC is fully operational, allow queries */
>>>> clear_bit(EC_FLAGS_QUERY_PENDING,&ec->flags);
>>>> +
>>>> + /* Some hardware may need the EC to be cleared before use */
>>>>
>>>>
>>> description is implicit, should specify what we clear is Q event, not EC.
>>>
>>> Thanks!
>>> Li Guang
>>>
>>>
>>>> + if (EC_FLAGS_CLEAR_ON_RESUME) {
>>>> + mutex_lock(&ec->mutex);
>>>> + acpi_ec_clear(ec);
>>>> + mutex_unlock(&ec->mutex);
>>>> + }
>>>> return ret;
>>>> }
>>>>
>>>> @@ -922,6 +956,30 @@ static int ec_enlarge_storm_threshold(const struct dmi_system_id *id)
>>>> return 0;
>>>> }
>>>>
>>>> +/*
>>>> + * On some hardware it is necessary to clear events accumulated by the EC during
>>>> + * sleep. These ECs stop reporting GPEs until they are manually polled, if too
>>>> + * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
>>>> + *
>>>> + * https://bugzilla.kernel.org/show_bug.cgi?id=44161
>>>> + *
>>>> + * Ideally, the EC should also be instructed not to accumulate events during
>>>> + * sleep (which Windows seems to do somehow), but the interface to control this
>>>> + * behaviour is not known at this time.
>>>> + *
>>>> + * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
>>>> + * however it is very likely that other Samsung models are affected.
>>>> + *
>>>> + * On systems which don't accumulate EC events during sleep, this extra check
>>>> + * should be harmless.
>>>> + */
>>>> +static int ec_clear_on_resume(const struct dmi_system_id *id)
>>>> +{
>>>> + pr_debug("Detected system needing EC poll on resume.\n");
>>>> + EC_FLAGS_CLEAR_ON_RESUME = 1;
>>>> + return 0;
>>>> +}
>>>> +
>>>> static struct dmi_system_id ec_dmi_table[] __initdata = {
>>>> {
>>>> ec_skip_dsdt_scan, "Compal JFL92", {
>>>> @@ -965,6 +1023,9 @@ static struct dmi_system_id ec_dmi_table[] __initdata = {
>>>> ec_validate_ecdt, "ASUS hardware", {
>>>> DMI_MATCH(DMI_SYS_VENDOR, "ASUSTek Computer Inc."),
>>>> DMI_MATCH(DMI_PRODUCT_NAME, "L4R"),}, NULL},
>>>> + {
>>>> + ec_clear_on_resume, "Samsung hardware", {
>>>> + DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
>>>> {},
>>>> };
>>>>
>>>>
>>>>
>>>
>>>
>> --
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