On Tue, Jun 12, 2007 at 09:54:59AM +0800, Wang Zhenyu wrote:
> It looks that config space save/restore for intel-agp still has problem
> that might affect some chip models. Andreas Mohr's work on his i815
> suspend/resume
> support showed that we need to save extra bits in config space on this old
> chip type.
> His patch is in -mm tree,
> http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-rc4/2.6.22-rc4-mm2/broken-out/working-3d-dri-intel-agpko-resume-for-i815-chip.patch
>
> And recently James Bottomley also reported that save/restore whole 256 bytes
> config
> space for gfx device can fix his s3 issue on Fujitsu P7120 i915.
> http://lists.freedesktop.org/archives/xorg/2007-June/025346.html
>
> So here's my suggested patch for save whole 256 bytes config space for
> intel-agp,
> which could fix these issues. I tested it on my 965GM, that s3 works fine
> with X.
I'd feel much safer if we only did this on chipsets where we know we
have to do it. Doing this for *every* Intel chipset ever made _will_
bite us. There are some early chipsets (440BX era iirc) that would just
hang the box when you tried to read from various write-only registers.
But even on the chipsets where we _do_ need to save/restore something in
the upper part of the config space, surely it'd be a lot safer
to just save/restore what we need to rather than risk all sorts
of mayhem by writing to bits that may trigger hardware events.
Dave
--
http://www.codemonkey.org.uk
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