linux-kernel - Re: ISA -> ISA_ (Re: [GIT PATCH] ACPI patches for 2.6.25-rc6)

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Message-Id: <200803260956.55804.bjorn.helgaas@hp.com>
Date:	Wed, 26 Mar 2008 09:56:53 -0600
From:	Bjorn Helgaas <bjorn.helgaas@...com>
To:	Len Brown <lenb@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Corentin CHARY <corentincj@...aif.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pm@...ts.linux-foundation.org
Subject: Re: ISA -> ISA_ (Re: [GIT PATCH] ACPI patches for 2.6.25-rc6)

On Wednesday 26 March 2008 09:32:20 am Len Brown wrote:
> >  /* Here we go */
> > -#define A1x_PREFIX "\\_SB.PCI0.ISA.EC0."
> > +#define A1x_PREFIX "\\_SB.PCI0.ISA_.EC0."
> 
> From an AML point of view, ISA is just as legal as "ISA_"
> The NameString paramter to Device() can be 1 to 4 characters.
> 
> So if this is correct or not depends on what the BIOS programmer
> for the Asus A1x choose to write.  Perhaps Corentin 'Iksaif' CHARY
> can confirm if the driver is working properly on that system.

I'm curious about how this works.  I disassembled the DSDT from
http://bugzilla.kernel.org/show_bug.cgi?id=4773 (I attached the disassembly
at http://bugzilla.kernel.org/attachment.cgi?id=15448&action=view), and
the _PRT contains "_SB" and "ISA" (no trailing underscores):

                Package (0x04)
                {
                    0x000DFFFF, 
                    0x00, 
                    \_SB.PCI0.ISA.LNKA, 
                    0x00
                }

But by the time we get to acpi_pci_irq_add_entry(), we've added the
underscores somewhere (see
http://bugzilla.kernel.org/attachment.cgi?id=15423&action=view):

  0000:00:0d[A] -> \_SB_.PCI0.ISA_.LNKA

I don't know where this happens, but it certainly confused me, and
it seems like it could lead to other bugs.

Bjorn
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