[ECOS] Re:IXP425 UART Problem
Wed Nov 29 11:23:00 GMT 2006
"Jamaluddin Khan" <firstname.lastname@example.org> writes:
> > Hi,
> > We are running redboot on IXP 425 platform. The IXP425 has a known bug
> > that when the UART break indicator (fourth bit of LSR) is de-asserted,
> > it is possible for the UART to detect a start bit and receive an
> > incorrect 0xFF byte. And this bug is not fixed.
> > So when this incorrect 0xFF byte received the bootloader goes in
> > blocking read mon_read_char() and the bootloader gets stuck up there.
> > Does anybody have any workaround for this?
> >You could try fixing it in the driver: after detecting a break throw
> >away any 0xFF bytes received.
> >It may also be worthwhile working out why you are getting breaks in
> >the first place.
> >Nick Garnett
> The bug is when the UART break indicator (fourth bit of LSR) is
> de-asserted (made zero),it is possible for the UART to detect a start
> bit and receive an incorrect 0xFF byte.
> There is no problem when the break indicator is one. The problem
> could when the UART break indicator(fourth bit of LSR)is zero.The Break
> indicator is reset when the processor reads the Line Status
Presumably for this bit to transition from one to zero it must have
transitioned from zero to one at some point. That transition was
presumably as a result of a break condition which you can detect, by
inspecting this bit. At this point you can presumably look for 0xFF
bytes and discard them.
Nick Garnett eCos Kernel Architect
http://www.ecoscentric.com The eCos and RedBoot experts
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