Re: 2.6.23-rc8-mm1, -rc7-mm1 kill audio on HP nx6325

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 25 Sep 2007 13:53:51 +0200 "Rafael J. Wysocki" <rjw@sisk.pl> wrote:

> Hi,
> 
> This patch from Andi:
> 
> x86_64-mm-cpa-einval.patch
> 
> makes the hda_intel audio driver stop working on my HP nx6325.
> 
> The following line appears in dmesg (from 2.6.23-rc7-mm1:
> 
> ALSA /home/rafael/src/mm/linux-2.6.23-rc7-mm1/sound/pci/hda/hda_intel.c:1755: hd
> a-intel: ioremap error
> 
> and the driver doesn't work afterwards.
> 
> Still, I'm not sure if the patch above is wrong or rather it exposes a problem
> in the driver.
> 

Mysterious.

ioremap_nocache() does __ioremap(..., _PAGE_PCD);, then __ioremap() does
ioremap_page_range(..., _PAGE_PCD | other_stuff) That's one.

__ioremap() then does ioremap_change_attr(..., _PAGE_PCD);.  That's two.

So I _think_ we're setting _PAGE_PCD twice on those pte's?  Unclear.  The
implementation is rather different from i386, too.

I dunno why __change_page_attr() failed though.  Perhaps this, in
change_page_attr_addr():

		if (!kernel_map || pte_present(pfn_pte(0, prot))) {

should be &&

Andi's taking a bit of time off, so we may need to park this until he
resurfaces.