Re: timer interrupt handler in blob

[Abraham vd M. <ab...@2d...>]

Hi Erik!

> > At the moment, I've just added a hook in my hardware initialization rou=
tine
> > to setup my interrupt handler at 0x0018 and program the OS timer to tri=
gger
> > irq 26 every 400ms. That way I don't mess around with the generic stuff.
>=20
> The generic code is pretty easy, and the interrupt system works the
> same on all ARM CPUs anyway, so I'd rather think it belonged there :)

Ok, I'll take a look at start.S

> > > blob. All watchdog devices I know have an option that they aren't
> > > enabled at boot time, but only start working after you first use them.
> >=20
> > This one can't be disabled which is as it should be. If you can disable=
 it
> > in software the whole idea of a watchdog is flawed...
>=20
> No, the watchdog you're using right now is brain damaged. Every
> watchdog I know is disabled at hardware reset and should be enabled by
> the OS. The OS just can't *disable* the watchdog, though. This
> enable-but-can't-disable feature was made exactly because it allows the
> system to initialise itself.

So how do you prevent the OS from disabling the watchdog. If there is a way
to disable the watchdog during boot time it is theoretically possible that
something in the OS can disable it again by mistake - this is obviously not
likely to happen, but possible. We have a watchdog exactly to prevent this,
so I think a watchdog that can be disabled during startup is brain damaged.

> > > It's not that I am against adding features in blob, it's just that I
> > > don't see a point in adding useless features.
> >=20
> > I totally agree, but in this case it's kind of necessary in order to ge=
t a
> > functional board.
>=20
> Please double check the data sheet. I just can't believe there is such

Its a Dallas DS1832 chip - it has to be strobed periodically once it
receives power.

> crap watchdog hardware on the market. If you have an option to change
> the hardware, consider using a better watchdog.

Hehe, if you can convince me that it's not necessary I can change it, but
you still haven't convinced me that being able to disable a watchdog is a
good thing.

--=20

Regards
 Abraham

Love tells us many things that are not so.
		-- Krainian Proverb

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 Abraham vd Merwe - 2d3D, Inc.

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