[PATCH v2 0/9] ACPICA: Improve GPE handling model.

Lv Zheng
2014-07-15T03:07:28Z

This patchset enables the ideal GPE handling model. The ideal GPE handling
model should be able to handle the following cases:

1. When upper layers (the users of the driver) submit requests to the
drivers, it means they care about the underlying hardware. For this
case, acpi_enable_gpe() should be invoked. When the reference count
is increased from 0 to 1, driver enables the hardware IRQ. And
acpi_disable_gpe() is used as the reversal when the users have
completed the submitted requests.
2. Driver may temporarily disables the IRQ and wants to re-enable it
later, this case is normally used in order to prevent IRQ storm.
When a driver cannot fully solve the condition that triggered the IRQ
in the IRQ context, in order not to trigger IRQ storm, driver has to
disable IRQ and re-enables it in the deferred execution environment
- which should be in a task context. The acpi_set_gpe() API should be
used exactly for this purpose.

The reason why this model hasn't been enabled for the current Linux ACPI
drivers is:
In ACPICA, the same GPE lock is held while invoking the GPE handler
callback, it's thus impossible to invoke GPE APIs in the GPE handler
because the APIs require to hold the GPE lock. The recursive locking
leads to dead locks. This is a simple design defect, callbacks should
always be invoked in a lockless environment, normally in Linux, this is
achieved by RCU locking, and in ACPICA, we achieve this using reference
counting.

After fixing the above bug and doing necessary cleanups in the ACPICA GPE
handling code, we now can enable this ideal GPE handling model for the EC
driver to implement "commands flushing" and "storm prevention" (the EC
driver enabling is not included in this patchset).

The refined patches are passed the runtime/suspend tests carried out on the
following platforms with EC driver enhanced:
"Dell Inspiron Mini 1010" - i386 kernel
"Dell Latitude 6430u" - x86_64 kernel

Lv Zheng (9):
ACPICA: Events: Reduce indent divergences of events files.
ACPICA: Events: Fix an issue that GPE APIs cannot be invoked in
atomic context.
ACPICA: Events: Fix an issue that GPE APIs cannot be invoked in
deferred handlers.
ACPICA: Events: Introduce acpi_set_gpe()/acpi_finish_gpe() to reduce
divergences.
ACPICA: Events: Fix an issue that acpi_set_gpe() cannot
unconditionally enable GPEs.
ACPICA: Events: Fix an issue that status of GPEs are unexpectedly
cleared.
ACPICA: Events: Fix an issue that originally_enabled check is not
paired.
ACPICA: Events: Add a flag to disable internal auto GPE clearing.
ACPI: Update interrupt handler to honor new ACPI_REENABLE_GPE bit.

drivers/acpi/acpica/acevents.h | 1 +
drivers/acpi/acpica/aclocal.h | 5 +-
drivers/acpi/acpica/evgpe.c | 136 +++++++++++++++++++++-------------------
drivers/acpi/acpica/evxface.c | 41 ++++++++----
drivers/acpi/acpica/evxfgpe.c | 105 +++++++++++++++++++++++++++++++
drivers/acpi/osl.c | 2 +-
include/acpi/actypes.h | 16 ++---
7 files changed, 219 insertions(+), 87 deletions(-)

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1.7.10