[U-Boot] Question about interrupt-driven mode duart on MPC837xE-rdb board.(with the subject)

[shawn Bai]

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> Date: Sun, 14 Aug 2011 16:25:35 +0200
> From: albert.u.boot at aribaud.net
> To: programassem at hotmail.com
> CC: u-boot at lists.denx.de
> Subject: Re: [U-Boot] Question about interrupt-driven mode duart on MPC837xE-rdb board.(with the subject)
>
> Le 14/08/2011 05:10, shawn Bai a écrit :
>
> > >Hi Shawn,
> > >Le 13/08/2011 17:33, shawn Bai a écrit :
> > >>
> > >>
> > >> Hello, guys.
> > >>
> > >> I have 2 questions about duart on MPC837xE-rdb board.
> > >>
> > >> 1. why not implement duart driver in interrupt-driven mode, in addition to polling-mode?
> > >>
> > >> from the existing implementation of uboot, I find there is only polling-mode duart driver.
> >
> > >Well, why would interrupts be needed for? Remember that U-Boot is not a
> > >multi-tasking OS, but a single-thread bootloader, so we tend to use
> > >interrupts only if there is a good case for it as far as bootloading is
> > >concerned.
> >
> > Well, I see. This is the answer I wanna know for a period of time.
> >
> > Speaking of interrupt-driven mode DUART, it depens on the requirement from upper application.
> >
> > DUART is used in redundant communication. Each end on DUART has no idea when the data from the other
> >
> > end will come. and the cpu time cannot be wasted on waiting, even a little. So interrupt-driven mode
> >
> > DUART is what we want.
>
> Well... If you cannot waste even a little CPU time on waiting for the
> UART, that pretty much amounts to saying you cannot work from inside a
> bootloader; you need a real-time OS. That's the reason they exist.