Re: [Bug #13318] AGP doesn't work anymore on nforce2

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

On Tuesday 07 July 2009 13:00:11 Rafael J. Wysocki wrote:
> On Tuesday 07 July 2009, Shaohua Li wrote:
> > On Tue, Jul 07, 2009 at 08:00:36AM +0800, Rafael J. Wysocki wrote:
> > > This message has been generated automatically as a part of a report
> > > of regressions introduced between 2.6.29 and 2.6.30.
> > > 
> > > The following bug entry is on the current list of known regressions
> > > introduced between 2.6.29 and 2.6.30.  Please verify if it still should
> > > be listed and let me know (either way).
> > > 
> > > 
> > > Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13318
> > > Subject		: AGP doesn't work anymore on nforce2
> > > Submitter	: Karsten Mehrhoff <kawime@gmx.de>
> > > Date		: 2009-04-30 8:51 (68 days old)
> > > First-Bad-Commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=59de2bebabc5027f93df999d59cc65df591c3e6e
> > > References	: http://marc.info/?l=linux-kernel&m=124108156417560&w=4
> > > Handled-By	: Shaohua Li <shaohua.li@intel.com>
> > Can anybody else help look at this issue? I really have no idea why this could
> > happens.
> 
> Quirky hardware?

Could be a weird interaction between CONFIG_X86_USE_3DNOW and AGP
or "simply" some timing issue.  Either way it means a lot of "fun". ;)

The latter theory can be verified by adding some {u,m}delay() to
agp_generic_alloc_page{s}() and the former one with:

---
 arch/x86/Kconfig.cpu |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: b/arch/x86/Kconfig.cpu
===================================================================
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -363,7 +363,7 @@ config X86_USE_PPRO_CHECKSUM
 
 config X86_USE_3DNOW
 	def_bool y
-	depends on (MCYRIXIII || MK7 || MGEODE_LX) && !UML
+	depends on (MCYRIXIII || MGEODE_LX) && !UML
 
 config X86_OOSTORE
 	def_bool y