linux-kernel - Re: has the i915 "black screen" boot issue returned? [BISECTED]

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Date:	Fri, 28 Jan 2011 09:10:12 -0500 (EST)
From:	"Robert P. J. Day" <rpjday@...shcourse.ca>
To:	Chris Wilson <chris@...is-wilson.co.uk>
cc:	dri-devel@...ts.freedesktop.org, Len Brown <len.brown@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org
Subject: Re: has the i915 "black screen" boot issue returned? [BISECTED]

On Fri, 28 Jan 2011, Chris Wilson wrote:

> On Fri, 28 Jan 2011 08:53:59 -0500 (EST), "Robert P. J. Day" <rpjday@...shcourse.ca> wrote:
> > so the culprit appears to be:
> >
> > b705120e4198315f4ae043de06c62f65e0851fd3 is the first bad commit
> > commit b705120e4198315f4ae043de06c62f65e0851fd3
> > Author: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
> > Date:   Sun Jan 23 18:17:17 2011 +0000
> >
> >     drm/i915: Use consistent mappings for OpRegion between ACPI and i915
> >
> >     The opregion is a shared memory region between ACPI and the graphics
> >     driver. As the ACPI mapping has been changed to cachable in commit
> >     6d5bbf00d251cc73223a71422d69e069dc2e0b8d, mapping the intel opregion
> >     non-cachable now fails. As no bus-master hardware is involved in the
> >     opregion, cachable map should do no harm.
> >
> >     Tested on a Fujitsu Lifebook P8010.
> >
> >     Signed-off-by: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
> >     [ickle: convert to acpi_os_ioremap for consistency]
> >     Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
> >
> >
> >   thoughts?  once again, the salient output from "lspci -v":
>
> Indeed looks like using ioremap_cache is not as safe as was assumed. Does

  *sigh*.  there was, in fact, an "ioremap_error" message displayed
*very* early in the boot sequence, but it was generated even for
successful boots so i never paid it any mind.  in hindsight, might
have been useful to have mentioned it.

> diff --git a/include/linux/acpi_io.h b/include/linux/acpi_io.h
> index 7180013..42108ab 100644
> --- a/include/linux/acpi_io.h
> +++ b/include/linux/acpi_io.h
> @@ -7,7 +7,7 @@
>  static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
>                                             acpi_size size)
>  {
> -       return ioremap_cache(phys, size);
> +       return ioremap_wc(phys, size);
>  }
>
>  int acpi_os_map_generic_address(struct acpi_generic_address *addr);

  ok, i'll make this single change and report back shortly.

rday

-- 

========================================================================
Robert P. J. Day                               Waterloo, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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