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SubjectRe: Is acpi_ec_ecdt_probe() broken? (was: Re: ACPI locks hardware devices when it doesn't detect vista)
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On Sat, 2009-08-29 at 21:40 +0200, Rafael J. Wysocki wrote:
> On Saturday 29 August 2009, 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.
>
> This is a bug IMO. Len, what do you think?
>
> > 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?
>
> To my eyes, this problem is a result of a workaround in acpi_ec_ecdt_probe(),
> that according to the comment in there "is needed only on some broken machines
> which require early EC, but fail to provide ECDT".
>
> You probably wrote that in one of the previous messages, but is your machine an
> ASUS one by chance?
>
> Len, really, the things done by acpi_ec_ecdt_probe() in case ECDT is not found
> don't look good to me at all.
>
> Why do we run the workaround for everyone, not just for _the_ broken systems?
>
> Moreover, why is "ASUS" hardcoded into the function as a known bad vendor
> rather than put into a table?

No, Mairo's system is a compal laptop, and I know that it does't have a
ECDT (as well as mine btw, today hardware is quite similar)

On top of that, I have asked Mairo to put acpi_ec_ecdt_probe(); just
below the acpi_initialize_objects, but he said his system didn't boot
after this change.

_SB._INI does some black SMI magic that might need a EC after all.

For reference, I attach acpidump of his system, and dmesg with some acpi
debugging enabled.

Mairo, could you post output of dmidecode, so I know exactly the laptop
model.


Best regards,
Maxim Levitsky

>
> Thanks,
> Rafael
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