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

Zheng, Lv
2014-07-16T00:37:22Z

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Hi,

> From: Rafael J. Wysocki [mailto:rjw@rjwysocki.net]
> Sent: Tuesday, July 15, 2014 8:26 PM
>
> On Tuesday, July 15, 2014 11:07:10 AM Lv Zheng wrote:
> > 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).
>
> How this patch series is related to upstream ACPICA? Is the design fixed
> already upstream?

It hasn't been upstreamed to the ACPICA repo.

This series has been sent to ACPICA upstream as a github pull request, reviewed by David Box.
We are waiting for it to be merged.

This series is required by the EC storm fix series.
I sent both the storm fix series and the linuxized GPE series here, so that we can examine a real OSPM example to see the effect of the new APIs.

Thanks and best regards
-Lv

>
> > 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(-)
> >
> >
>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
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