Re: Re: acpi on new gateway laptops

[Ducrot Bruno <ducrot-kk6yZipjEM5g9hUCZPvPmw@public.gmane.org>]

On Wed, Nov 12, 2003 at 06:33:28PM -0500, William Morgan wrote:
> Heh. Didn't mean to hit send quite so fast. :)
> 
> For context, the two threads are:
> http://sourceforge.net/mailarchive/message.php?msg_id=6229363 and
> http://sourceforge.net/mailarchive/message.php?msg_id=6319180
> 
> In both cases /proc/battery is empty and it has been suggested that we
> are missing an ECDT table and should (somehow) provide one.
> 
> For those in the know about ACPI, comments would be greatly appreciated
> on these two issues:
> 
> First:
> 
>  [According to the ACPI spec] It seems like having an ECDT is an
>  optional feature?

yes.  ECDT do not exist in ACPI 1.0, and ACPI 2.0 claims to be
compatible.  Then ECDT can only be optional.

>  If that's so, then what's the problem? Why isn't
>  Linux simply "discovering and enumerating" the "Embedded Controller
>  device in the AML namespace"?

because you can not use EC when _STA nor _INI.  Or if you know
already that you have an EC (but without ECDT), then you have already
executed the _STA associated to the EC.  Chick-and-egg problem.

> Second, does this scenario make any sense:
> 
>  There's an Embedded Controller region (In the BIOS? In the DSDT?). One
>  cannot access a region until registering it, by calling
>  _REG(RegionSpace, 1). There's an exception to this, however, when using
>  an ECDT, which describes "controllers" (?) to access the Embedded
>  Controller region. If you have an ECDT you can then access this region
>  before registering it. So I think that's what the DSDT is doing, but
>  without providing an ECDT?

The DSDT does nothing.  This is only a table that contain a language.
ECDT is a table, also.  It is not in DSDT.


> Third, would this solution work?
> 
>  Rather than provide an ECDT, we can alternately try and fix the DSDT.

Most of ACPI 1.0 compliant system (before ACPI 2.0) implement a _REG
method which basically make a kind of boolean.  Then you look if
that boolean is true, or false.  This have though some incorrect behaviour,
like 'discovering' at boot that there are 2 batteries fully charged
for example.  Note also that thinkpad does actually the two, and check
the \_REV  in a _INI method to see if it is a ACPI 2, or not.  Im not
sure that is a good idea from IBM.

I think that we should do a fake ECDT option.  That is
straightforward to implement anyway.

-- 
Ducrot Bruno

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.


-------------------------------------------------------
This SF.Net email sponsored by: ApacheCon 2003,
16-19 November in Las Vegas. Learn firsthand the latest
developments in Apache, PHP, Perl, XML, Java, MySQL,
WebDAV, and more! http://www.apachecon.com/