[i2c] Question on ds1339's oscillator

[Rodolfo Giometti]

On Sat, Jun 16, 2007 at 11:10:24AM -0700, David Brownell wrote:
> 
> Go back and read the chip specs again.  The bit name is "nEOSC",
> indicating by the "n" that it's active low.  So nEOSC low means
> EOSC high, and thus the oscillator is OK...

Yes, I read correctly, the bit was high. That's why I got the message
"no ascillator code" and the error.

> Yet ... you didn't address my question.  You're suggesting that
> Linux ignore information it's been given, and change system config
> in a way that could *break* something.  Plus, why force square wave
> output for IRQ-less configs?  That costs power, among other things,
> and the pin isn't necessarily intended to host such a signal.

Maybe I wrote wrong. :)

I ment that if the user specify an IRQ line then the the driver should
force bit INTCN to 1.

> That would explain why the kernel never has bugs to fix.
> Oh, wait a second ... it's huge, and DOES have lots of bugs
> to fix.  Scratch that, then.  Your assumption is wrong.
> 
> I've seen lots of folk just copy'n'paste code from one platform
> into another, even when a simple check of the schematics would
> show that's clearly wrong.  (Maybe they didn't have schematics
> right then, or were in a hurry, or ...)
> 
> In this case the hardware configuration can tell us if the
> kernel config doesn't match the hardware.  But there's no way
> to tell how to resolve the mismatch without schematics.

Is not a Linux fault if most of us use too much the cut-and-paste
functionality. :)

However if the developer specifies an IRQ line than the pin output
must be forced.

> Which is way I said this is normally a manufacturing role,
> just like setting the clock in the first place.  Remember
> these particular values don't get reset at boot.  Most of
> the time, bootloaders have no reason to look at any RTC.
> They just set up some pin configuration, memory timings,
> and load the kernel.

Okokok, even if the settings are not lost at reboot I think is not
wrong re-setting them.

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti at enneenne.com
Linux Device Driver                             giometti at gnudd.com
Embedded Systems                     		giometti at linux.it
UNIX programming                     phone:     +39 349 2432127
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