linux-kernel - Re: 2.6.24-rc8 hangs at mfgpt-timer

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Message-Id: <200801221111.21240.hel@admin.de>
Date:	Tue, 22 Jan 2008 11:11:20 +0100
From:	Lars Heete <hel@...in.de>
To:	Arnd Hannemann <hannemann@...informatik.rwth-aachen.de>
Cc:	Jordan Crouse <jordan.crouse@....com>,
	Andres Salomon <dilinger@...ued.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.24-rc8 hangs at mfgpt-timer

Hello,

On Tuesday 22 January 2008 10:03:08 am Arnd Hannemann wrote:
> Jordan Crouse wrote:
> > Okay - I've been exploring a little bit more.  I talked to the TinyBIOS
> > developer, and he verified that TinyBIOS shouldn't use any MFGPT timers.
> > He also told me that the mysterious "MFGPT workaround" was in fact the
> > magic MFGPT erasing MSR that was in the old kernel driver.
> >
> > So with the "MFGPT workaround" turned off, TinyBIOS should be acting like
> > the OLPC firmware with regards to timers, yet it is not.  So that is
> > curious.  I think I might have identified a race condition in the code,
> > but I'm not 100% sure thats the same problem that the ALIX platform is
> > seeing.
> >
> > Anrd and others - will you please try the attached patch on your platform
> > with the "MFGPT workaround" turned off and mfgpts enabled, and send out
> > the dmesg?
>
> Of course, tinyBios version v0.99, "MFGPT workaround" turned off,
> CONFIG_GEODE_MFGPT_TIMER=n:
>
> [   67.369697] NET: Registered protocol family 16
> [   67.383059] geode-mfgpt:  IRQ MSR=0:0
> [   67.394058] geode-mfgpt:  NMI MSR=0:0
> [   67.405049] geode-mfgpt:  Unrestricted sources=0
> [   67.418909] geode:  8 MFGPT timers available.
> [   67.433211] PCI: PCI BIOS revision 2.10 entry at 0xfcd03, last bus=0
>
> same with CONFIG_GEODE_MFGPT_TIMER=y (sorry, without move printk patch):
>
> [   22.289349] NET: Registered protocol family 16
> [   22.302716] geode-mfgpt:  IRQ MSR=0:0
> [   22.313716] geode-mfgpt:  NMI MSR=0:0
> [   22.324704] geode-mfgpt:  Unrestricted sources=0
> [   22.338566] geode-mfgpt:  Registered timer 0
> [   22.351393] mfgpt-timer:  registering the MFGT timer as a clock event.
> ^^^^ Hangs here
I had the same problem with MFGPT Timers and alix (BIOS v0.99). I found that 
if you use a different interrupt than the default 7 for MFGPT (just append 
mfgpt_irq=8 to the kernel commandline), the timer seems to work.

CPU0
  0:         33    XT-PIC-XT        timer
  2:          0    XT-PIC-XT        cascade
  4:       1662    XT-PIC-XT        serial
  8:        766    XT-PIC-XT        mfgpt-timer
 14:        473    XT-PIC-XT        libata
NMI:          0
ERR:          0


> > This will give us some debug information that I can use to ensure that
> > the interrupts are set up correctly.  You can leave the timer tick
> > disabled if you want.
> >
> >
> > Thanks,
> > Jordan
>
> Arnd

Lars
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