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    SubjectRe: [PATCH] ACPI / EC: Clear stale EC events on Samsung systems


    > that's really nasty EC firmware!

    Yes!
    And this bug has been unsolved for about two years.

    > 20 is enough?
    > the query index is length of a byte.
    >
    According to our humble tests, 8 is the maximum number of
    accumulated events. For instance, if the one plugs or unplugs the PSU
    16 times, (or battery % changes 16 times) during S3 sleep, then the
    EC returns no more than 8 events when polled by this patch or by
    my userspace util.
    And having reached 8 events, it won't produce its GPE until queried.

    > the query index is length of a byte.

    There is no query index, unless you refer to something else (I'm sorry if its
    something that escapes me).
    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@gmail.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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