[support-gang] Real time clock battery during XO storage
quozl at laptop.org
Mon Dec 9 22:18:51 EST 2013
On Mon, Dec 09, 2013 at 10:04:28PM -0500, Richard A. Smith wrote:
> On 12/09/2013 08:07 PM, James Cameron wrote:
> > The symptom is that pressing the power button gives about a one
> > second pulse on the power indicator, then it goes blank. There is
> > no serial cable output from the processor.
> Take a look at the EC output. It won't be as verbose as later
> generations but might provide some clues
Thanks. Indeed it does. We are hitting WorkingTimeout. The power
LED is driven for about 860 to 880ms.
DEEP_SLEEP -> RUNNING_STATE
> >The laptop starts fine with the RTC oscillator stopped, provided it
> >stopped because of removal of the RTC battery. It just won't start if
> >the RTC oscillator is stopped by writing to RTC control register.
> Seems to me that this is may be some sort of OFW issue. I seem to
> remember that we store some state in the RTC memory that is checked
> at early startup. Just stopping the OSC would leave the memory as
> is (I think). Perhaps that confuses OFW and its waiting for the
> something to respond that never will.
I like that idea, but I'm not getting a peep out of OFW. OFW doesn't
touch the RTC until the startup chain, which happens after serial
output begins. (i.e. after the 'i' to interact point).
> >Speculation: the XO-1 embedded controller is not detecting a 32 KHz
> >signal from ball C8, GPIO27, or is not detecting some other normal
> >response of the processor, and is abandoning the power up.
> Nope. Not for XO-1. Thats the SCI# signal and its an output from
> the EC (and not used). Unlike 1.5 and beyond in XO-1 there is
> minimal feedback to the EC about the state of the CPU booting. It's
> mostly just EC timers. I won't say its impossible but I don't have
> any memory of anything like that and a quick look at the system
> power up code doesn't bring back an memories.
Thanks, I'll have a closer look at the code.
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