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author | Compostella, Jeremy <jeremy.compostella@intel.com> | 2023-06-06 18:13:23 +0200 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2023-06-12 19:20:45 +0200 |
commit | 896e97bf99ecf0ecb6cc420bc2c9eb268d3edc05 (patch) | |
tree | ded77d9cc602dd85d14c000991909db6a96ccc24 /drivers | |
parent | Linux 6.4-rc6 (diff) | |
download | linux-896e97bf99ecf0ecb6cc420bc2c9eb268d3edc05.tar.xz linux-896e97bf99ecf0ecb6cc420bc2c9eb268d3edc05.zip |
ACPI: EC: Clear GPE on interrupt handling only
On multiple devices I work on, we noticed that
/sys/firmware/acpi/interrupts/sci_not is non-zero and keeps increasing
over time.
It turns out that there is a race condition between servicing a GPE
interrupt and handling task driven transactions.
If a GPE interrupt is received at the same time ec_poll() is running,
the advance_transaction() clears the GPE flag and the interrupt is not
serviced as acpi_ev_detect_gpe() relies on the GPE flag to call the
handler. As a result, `sci_not' is increased.
To address this, move the GPE status check and clearing from
advance_transaction() directly into acpi_ec_handle_interrupt(), so the
EC GPE only gets cleared in the interrupt handling path.
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/acpi/ec.c | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 928899ab9502..8569f55e55b6 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -662,21 +662,6 @@ static void advance_transaction(struct acpi_ec *ec, bool interrupt) ec_dbg_stm("%s (%d)", interrupt ? "IRQ" : "TASK", smp_processor_id()); - /* - * Clear GPE_STS upfront to allow subsequent hardware GPE_STS 0->1 - * changes to always trigger a GPE interrupt. - * - * GPE STS is a W1C register, which means: - * - * 1. Software can clear it without worrying about clearing the other - * GPEs' STS bits when the hardware sets them in parallel. - * - * 2. As long as software can ensure only clearing it when it is set, - * hardware won't set it in parallel. - */ - if (ec->gpe >= 0 && acpi_ec_gpe_status_set(ec)) - acpi_clear_gpe(NULL, ec->gpe); - status = acpi_ec_read_status(ec); /* @@ -1287,6 +1272,22 @@ static void acpi_ec_handle_interrupt(struct acpi_ec *ec) unsigned long flags; spin_lock_irqsave(&ec->lock, flags); + + /* + * Clear GPE_STS upfront to allow subsequent hardware GPE_STS 0->1 + * changes to always trigger a GPE interrupt. + * + * GPE STS is a W1C register, which means: + * + * 1. Software can clear it without worrying about clearing the other + * GPEs' STS bits when the hardware sets them in parallel. + * + * 2. As long as software can ensure only clearing it when it is set, + * hardware won't set it in parallel. + */ + if (ec->gpe >= 0 && acpi_ec_gpe_status_set(ec)) + acpi_clear_gpe(NULL, ec->gpe); + advance_transaction(ec, true); spin_unlock_irqrestore(&ec->lock, flags); } |