Oh, and cc linux-acpi....
On Sat, 2009-08-29 at 02:53 +0300, Maxim Levitsky wrote:
> On Sat, 2009-08-22 at 15:48 +0300, Maxim Levitsky wrote:
> > Hi,
> >
> > <joke>
> > This should be brought to a Microsoft antitrust case...
> > </joke>
> >
> >
> > Today many notebooks ship with a embedded infrared receiver.
> > In Vista there is new subsystem that decodes these signals.
> > (of course it works only with Microsoft Certificated Remotes (TM)...)
> >
> > The receiver is usually presented to system as a pnp device
> > (using acpi tables)
> >
> > It turns out that some bioses actually use the OSI, ACPI feature of the
> > operation system to detect if running inside Vista. If not they disable
> > the infrared receiver.
> >
> > Device (MIR)
> > {
> > Name (_HID, EisaId ("ENE0100"))
> > Method (_STA, 0, NotSerialized)
> > {
> > If (LAnd (MCIR, LEqual (OSYS, 0x07D6)))
> > {
> > Return (0x0F)
> > }
> > Else
> > {
> > Store (Zero, ^^LPCB.IOR2)
> > Return (Zero)
> > }
> > }
> >
> > .......
> >
>
> > Scope (_SB)
> > {
> > Method (_INI, 0, NotSerialized)
> > {
> ....
>
> > If (CondRefOf (_OSI, Local0))
> > {
> > If (_OSI ("Linux"))
> > {
> > Store (One, LINX)
> > Store (Zero, ECDY)
> > }
>
> ..........
> >
>
> > If (_OSI ("Windows 2006"))
> > {
> > Store (0x07D6, OSYS)
> > }
> .......
>
>
> I have finally managed to find root case of this problem.
>
> Indeed the _STA method of infrared receiver is called before the _INI of
> _SB.
>
> The problem lies in acpi_bus_init()
> /*
> * ACPI 2.0 requires the EC driver to be loaded and work before
> * the EC device is found in the namespace (i.e. before acpi_initialize_objects()
> * is called).
> *
> * This is accomplished by looking for the ECDT table, and getting
> * the EC parameters out of that.
> */
>
> status = acpi_ec_ecdt_probe();
> /* Ignore result. Not having an ECDT is not fatal. */
>
> status = acpi_initialize_objects(ACPI_FULL_INITIALIZATION);
> if (ACPI_FAILURE(status)) {
> printk(KERN_ERR PREFIX "Unable to initialize ACPI objects\n");
> goto error1;
> }
> .......
>
>
> on Mairo's system (just as well as on mine) there is no ECDT.
> Thus, acpi_ec_ecdt_probe() triggers a acpi namespace walk,
> which in turn triggers invocation on _STA (which is supposed to be
> harmless, but the <beep>, the bios developers produce doesn't seem to
> meet this criteria....).
>
> And this is done before running _INI methods, which are run just later,
> in acpi_initialize_objects.
>
> I suspect that many systems use _SB._INI to test the OS version, thus
> this behavior needs to be revised.
>
> The fact that this (as usual) works in windows suggest that it might be
> good to look up the ECDT table before acpi_initialize_objects, but if
> not found, look up the EC later.
>
> On my system, although I have tried to reproduce this bug, I couldn't,
> and I know now why: It just so happens that on my system CIR device is
> listed in acpi tables after the EC, but on Mairo's system EC is just
> first device.
>
> Maybe we can add a 'walk only' function, that walks the namespace, but
> doesn't touch the _STA, and use it to find the EC there?
>
> Looking for comments,
> Best regards,
> Maxim Levitsky
>
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