[3.8.y.z extended stable] Patch "ACPI / EC: Clear stale EC events on Samsung systems" has been added to staging queue
D. G. Jansen
d.g.jansen at gmail.com
Fri Mar 28 14:38:11 UTC 2014
Dear Kamal,
please wait for now as a slight regression was reported for one system and
the patch will be changed.
Best,
Dennis
Am Freitag, 28. März 2014 schrieb Kamal Mostafa :
> This is a note to let you know that I have just added a patch titled
>
> ACPI / EC: Clear stale EC events on Samsung systems
>
> to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree
> which can be found at:
>
>
> http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue
>
> This patch is scheduled to be released in version 3.8.13.21.
>
> If you, or anyone else, feels it should not be added to this tree, please
> reply to this email.
>
> For more information about the 3.8.y.z tree, see
> https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
>
> Thanks.
> -Kamal
>
> ------
>
> From 1393f3f58ecb25d9ce797d30baf41eeccf975516 Mon Sep 17 00:00:00 2001
> From: Kieran Clancy <clancy.kieran at gmail.com <javascript:;>>
> Date: Sat, 1 Mar 2014 00:42:28 +1030
> Subject: ACPI / EC: Clear stale EC events on Samsung systems
>
> commit ad332c8a45330d170bb38b95209de449b31cd1b4 upstream.
>
> A number of Samsung notebooks (530Uxx/535Uxx/540Uxx/550Pxx/900Xxx/etc)
> continue to log events during sleep (lid open/close, AC plug/unplug,
> battery level change), which accumulate in the EC until a buffer fills.
> After the buffer is full (tests suggest it holds 8 events), GPEs stop
> being triggered for new events. This state persists on wake or even on
> power cycle, and prevents new events from being registered until the EC
> is manually polled.
>
> This is the root cause of a number of bugs, including AC not being
> detected properly, lid close not triggering suspend, and low ambient
> light not triggering the keyboard backlight. The bug also seemed to be
> responsible for performance issues on at least one user's machine.
>
> Juan Manuel Cabo found the cause of bug and the workaround of polling
> the EC manually on wake.
>
> The loop which clears the stale events is based on an earlier patch by
> Lan Tianyu (see referenced attachment).
>
> This patch:
> - Adds a function acpi_ec_clear() which polls the EC for stale _Q
> events at most ACPI_EC_CLEAR_MAX (currently 100) times. A warning is
> logged if this limit is reached.
> - Adds a flag EC_FLAGS_CLEAR_ON_RESUME which is set to 1 if the DMI
> system vendor is Samsung. This check could be replaced by several
> more specific DMI vendor/product pairs, but it's likely that the bug
> affects more Samsung products than just the five series mentioned
> above. Further, it should not be harmful to run acpi_ec_clear() on
> systems without the bug; it will return immediately after finding no
> data waiting.
> - Runs acpi_ec_clear() on initialisation (boot), from acpi_ec_add()
> - Runs acpi_ec_clear() on wake, from acpi_ec_unblock_transactions()
>
> References: https://bugzilla.kernel.org/show_bug.cgi?id=44161
> References: https://bugzilla.kernel.org/show_bug.cgi?id=45461
> References: https://bugzilla.kernel.org/show_bug.cgi?id=57271
> References: https://bugzilla.kernel.org/attachment.cgi?id=126801
> Suggested-by: Juan Manuel Cabo <juanmanuel.cabo at gmail.com <javascript:;>>
> Signed-off-by: Kieran Clancy <clancy.kieran at gmail.com <javascript:;>>
> Reviewed-by: Lan Tianyu <tianyu.lan at intel.com <javascript:;>>
> Reviewed-by: Dennis Jansen <dennis.jansen at web.de <javascript:;>>
> Tested-by: Kieran Clancy <clancy.kieran at gmail.com <javascript:;>>
> Tested-by: Juan Manuel Cabo <juanmanuel.cabo at gmail.com <javascript:;>>
> Tested-by: Dennis Jansen <dennis.jansen at web.de <javascript:;>>
> Tested-by: Maurizio D'Addona <mauritiusdadd at gmail.com <javascript:;>>
> Tested-by: San Zamoyski <san at plusnet.pl <javascript:;>>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com<javascript:;>
> >
> [ kamal: backport to 3.8 (context) ]
> Signed-off-by: Kamal Mostafa <kamal at canonical.com <javascript:;>>
> ---
> drivers/acpi/ec.c | 64
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
> index 97fcfb0..092f862 100644
> --- a/drivers/acpi/ec.c
> +++ b/drivers/acpi/ec.c
> @@ -70,6 +70,8 @@ enum ec_command {
> #define ACPI_EC_DELAY 500 /* Wait 500ms max. during EC ops */
> #define ACPI_EC_UDELAY_GLK 1000 /* Wait 1ms max. to get global
> lock */
> #define ACPI_EC_MSI_UDELAY 550 /* Wait 550us for MSI EC */
> +#define ACPI_EC_CLEAR_MAX 100 /* Maximum number of events to
> query
> + * when trying to clear the EC */
>
> enum {
> EC_FLAGS_QUERY_PENDING, /* Query is pending */
> @@ -123,6 +125,7 @@ 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; /* Needs acpi_ec_clear() on
> boot/resume */
>
> /*
> --------------------------------------------------------------------------
> Transaction Management
> @@ -468,6 +471,29 @@ acpi_handle ec_get_handle(void)
>
> EXPORT_SYMBOL(ec_get_handle);
>
> +static int acpi_ec_query_unlocked(struct acpi_ec *ec, u8 *data);
> +
> +/*
> + * Clears stale _Q events that might have accumulated in the EC.
> + * 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 (unlikely(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;
> @@ -491,6 +517,10 @@ 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);
> }
>
> @@ -848,6 +878,13 @@ static int acpi_ec_add(struct acpi_device *device)
>
> /* EC is fully operational, allow queries */
> clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
> +
> + /* Clear stale _Q events if hardware might require that */
> + if (EC_FLAGS_CLEAR_ON_RESUME) {
> + mutex_lock(&ec->mutex);
> + acpi_ec_clear(ec);
> + mutex_unlock(&ec->mutex);
> + }
> return ret;
> }
>
> @@ -949,6 +986,30 @@ 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 _Q 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 __initdata ec_dmi_table[] = {
> {
> ec_skip_dsdt_scan, "Compal JFL92", {
> @@ -992,6 +1053,9 @@ static struct dmi_system_id __initdata ec_dmi_table[]
> = {
> 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},
> {},
> };
>
> --
> 1.8.3.2
>
>
--
Dipl.-Jur. Dennis G. Jansen, LL.M. (Berkeley)
Tel. 0163 834 8558 | LinkedIn <https://www.linkedin.com/in/dennisgjansen/en>
Master of Laws, University of California, Berkeley, School of Law ("Boalt
Hall")
Certificate in Law and Technology, University of California, Berkeley,
School of Law ("Boalt Hall")
Certificate in Transnational Legal Studies, Georgetown University Law Center
Certificate in Internationalization of Law, Free University Berlin
Diploma of Law, Free University Berlin
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