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Re: [PATCH v3 10/15] acpi: parallel: don't use _STA method


From: Igor Mammedov
Subject: Re: [PATCH v3 10/15] acpi: parallel: don't use _STA method
Date: Mon, 4 May 2020 18:10:08 +0200

On Mon, 4 May 2020 15:25:16 +0200
Gerd Hoffmann <address@hidden> wrote:

> On Thu, Apr 30, 2020 at 06:25:24PM +0200, Igor Mammedov wrote:
> > On Wed, 29 Apr 2020 15:59:58 +0200
> > Gerd Hoffmann <address@hidden> wrote:
> >   
> > > The _STA method dates back to the days where we had a static DSDT.  The
> > > device is listed in the DSDT table unconditionally and the _STA method
> > > checks a bit in the isa bridge pci config space to figure whenever a
> > > given is isa device is present or not, then evaluates to 0x0f (present)
> > > or 0x00 (absent).
> > > 
> > > These days the DSDT is generated by qemu anyway, so if a device is not
> > > present we can simply drop it from the DSDT instead.
> > > 
> > > Signed-off-by: Gerd Hoffmann <address@hidden>
> > > Reviewed-by: Igor Mammedov <address@hidden>  
> > 
> > looking more at it, we should also cleanup no longer used LPEN field
> > the same applies to similar fields for serial and ...   
> 
> IIRC these bits are in the chipset specs so we should not remove them
> from pci config space.
we also can't touch device model due to migration resons
(ACPI code that checks STA bits is in the wild, and us removing ACPI part
of it won't change that)

> 
> Removing from DSDT should be possible indeed (I guess this is what you
> mean?)
yep

> 
> take care,
>   Gerd
> 




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