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

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Date:	Thu, 14 Feb 2008 13:07:58 -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 Mailing List <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 14 February 2008 12:42:52 pm Linus Torvalds wrote:
> 
> On Thu, 14 Feb 2008, Bjorn Helgaas wrote:
> > 
> > Sorry for the delay.  I did work on this, but I don't see how this
> > can work.  pcibios_init() marks its reservations as not busy, so the
> > subsequent PNP request doesn't fail, even if it clashes.
> 
> It *shouldn't* fail.
> 
> Things should fail only when two different drivers have requested the same 
> region. NOT when something tells the system that a region _exists_.

The sound driver doesn't fail because two different drivers have
requested the same region; it fails because PNP told us a region
exists, and the sound region crosses the edge of the PNP region.

You wrote earlier that:

> On Tue, 5 Feb 2008, Bjorn Helgaas wrote:
> > >  - PnP/ACPI resource allocation *after* it, but before driver
> > > loading (which wll cause new resources to be allocated). This
> > > could be fs_initcall, or whatever (that's what things like
> > > "acpi_event_init" already do).
> >
> > If we put the PNP system driver here, we can easily do a quirk
> > that ignores PNP resources that overlap PCI resources.
>
> No, you don't need any quirks: you just do an "insert_resource()"
> and ignore the error return. If the (bogus) PnP resource clashes
> with the (correct) hardware PCI resource, the insert will simply
> fail. No quirks needed.

I thought you were suggesting here that the PNP system driver would
do an insert_resource(), and it would fail if it clashed with the
PCI resource.

Can you be more explicit about how you think I should fix this?

Bjorn
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