linux-kernel - Re: ACPI locks hardware devices when it doesn't detect vista

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Message-Id: <1251571841.10321.1.camel@maxim-laptop>
Date:	Sat, 29 Aug 2009 21:50:41 +0300
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	linux-pm <linux-pm@...ts.linux-foundation.org>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Mairo <rety@...zta.onet.pl>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	lenb <lenb@...nel.org>
Subject: Re: ACPI locks hardware devices when it doesn't detect vista

What do you think to do in this case:

On Sat, 2009-08-29 at 03:40 +0300, Maxim Levitsky wrote:
> 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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