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    SubjectRe: [GEODE] Geode GX/LX watchdog timer (was 2.6.24-rc8 hangs at mfgpt-timer)
    On Fri, Jan 18, 2008 at 06:06:24PM -0700, Jordan Crouse wrote:
    > As promised, a watchdog driver for the Geode GX/LX processors is attached.
    > I basically just ported the previous patch forward to 2.6.24.
    > I also have good news or bad news depending on your perspective. I wanted
    > to test this against 2.6.24, and OLPC is stuck at an older kernel version,
    > so I had to test this with coreboot (LinuxBIOS) on another Geode
    > platform. Like all BIOSen execpt for the OLPC firmware, coreboot uses
    > VSA (SMM handler) which consumes all the timers.

    Hmm, the Geode LX platform I work with uses VSA/SMM and I have had no
    problems using timer 2 for a watchdog. Some of the timers are certainly
    already setup by something in the BIOS, but quite a few are not in use.
    The board I am using is the compulab iGLX module. I did have to mangle
    together a watchdog driver myself some time ago since there wasn't one
    for the Geode LX at the time.

    Of course I haven't gone past 2.6.18 kernel for now (I am tracking
    Debian stable for the most part), so I have no idea if something in a
    newer kernel breaks things.

    > So I used the magical MSR and surprise! - the timer tick hung.
    > I compiled out the timer tick, and tested the watchdog timer instead,
    > and it worked fine on timer 0. So I don't think the MFGPTs themselves
    > have anything to do with this problem, but I do think it might be
    > related to VSA and possibly interrupts too. I'm going to invoke the
    > strong BIOS fu of our LinuxBIOS / BIOS expert Marc Jones, and see what
    > he comes up with.
    > I don't know how much of a hassle it would be for Andres to get a 2.6.24
    > kernel running on the OLPC to make sure that this isn't a regression
    > in the timer tick code (I suspect it isn't a regression, but you never
    > know). I also think that it would probably be in our best interest to
    > default CONFIG_GEODE_MFGPT_TIMER to 'n' until we get this figured
    > out. Since most BIOSen don't have timers available, that shouldn't affect
    > too many people.
    > So, anyway, enjoy the watchdog timer - I hope it meets everybody's
    > expectations for the 2.6.25 kernel.

    Len Sorensen

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