linux-kernel - Re: a7839e96 (PNP: increase max resources) breaks my ALSA intel8x0 sound card

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Message-Id: <200802041039.36100.bjorn.helgaas@hp.com>
Date:	Mon, 4 Feb 2008 10:39:35 -0700
From:	Bjorn Helgaas <bjorn.helgaas@...com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Robert Hancock <hancockr@...w.ca>,
	Andrew Morton <akpm@...ux-foundation.org>, avuton@...il.com,
	yakui.zhao@...el.com, shaohua.li@...el.com, trenn@...e.de,
	linux-kernel@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: a7839e96 (PNP: increase max resources) breaks my ALSA intel8x0 sound card

On Thursday 31 January 2008 05:50:13 pm Linus Torvalds wrote:
> On Thu, 31 Jan 2008, Robert Hancock wrote:
> > 
> > I think so. There was one objection that it introduced a dependency on pnpacpi
> > loading after PCI bus enumeration, though.
> > 
> > Linus also suggested that pnpacpi could be marking the resources as "present
> > but unused" so that drivers can request those regions but we still prevent
> > dynamically assigning resources into them.
> 
> I _think_ that's what ACPI used to do before switching over to the PnPACPI 
> thing, so I do think that "present but not reserved" approach is not just 
> the right one, but also the (historically) tested one.

The reservation happens in drivers/pnp/system.c, and it does mark the
region as "not busy."

I think the problem here is that the PCI BAR is bigger and spans the
region reported by ACPI:

[   22.906654] system 00:08: iomem range 0xfebfa000-0xfebfac00 has been reserved
[   31.133141] PCI: Unable to reserve mem region #1:4000@...f8000 for device 0000:00:1b.0

We can easily add more BIOSes to the PNP quirk.

I really don't want to use the earlier quirk that scanned PCI devices
from a PNP quirk.  I think that's just wrong because PNP (which
conceptually includes ACPI) is what tells us about PCI root bridges.

Bjorn
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