mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-04-29 01:09:33 -04:00
1a373d15e2
Event codes are expected to be retrieved from a queue on at least some
models. Specifically, very likely the ACPI WMI devices with _UID ATK are
queued whereas those with ASUSWMI are not [1].
The WMI event codes are pushed into a circular buffer queue. After the INIT
method is called, ACPI code is allowed to push events into this buffer.
The INIT method cannot be reverted. If the module is unloaded and an event
(such as hotkey press) gets emitted before inserting it back the events get
processed delayed by one or if the queue overflows, additionally delayed by
about 3 seconds.
It might be considered a minor issue and no normal user would likely
observe this (there is little reason unloading the driver), but it does
significantly frustrate a developer who is unlucky enough to encounter
this. Therefore, the fallback to unqueued behavior occurs whenever
something unexpected happens.
The fix flushes the old key codes out of the queue on load. After receiving
event the queue is read until either ..FFFF or 1 is encountered. Also as
noted in [1] it is checked whether notify code is equal to 0xFF before
enabling queue processing in WMI notify handler.
DSDT examples:
FX505GM
Device (ATKD)
{ ..
Name (ATKQ, Package (0x10)
{
0xFFFFFFFF, ..
}
Method (IANQ, 1, Serialized)
{
If ((AQNO >= 0x10))
{
Local0 = 0x64
While ((Local0 && (AQNO >= 0x10)))
{
Local0--
Sleep (0x0A)
}
...
..
AQTI++
AQTI &= 0x0F
ATKQ [AQTI] = Arg0
...
}
Method (GANQ, 0, Serialized)
{
..
If (AQNO)
{
...
Local0 = DerefOf (ATKQ [AQHI])
AQHI++
AQHI &= 0x0F
Return (Local0)
}
Return (One)
}
This code is almost identical to K54C, which does return Ones on empty
queue.
K54C:
Method (GANQ, 0, Serialized)
{
If (AQNO)
{
...
Return (Local0)
}
Return (Ones)
}
[1] Link: https://lkml.org/lkml/2019/4/12/104
Signed-off-by: Yurii Pavlovskyi <yurii.pavlovskyi@gmail.com>
Suggested-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.