[U-Boot-Users] MPC5121 (and MPC5200) ethernet initialization delay
Stefan Roese
sr at denx.de
Tue Dec 18 10:03:41 CET 2007
On Tuesday 18 December 2007, Wolfgang Denk wrote:
> > autonegotiation only when the ethernet interface is used. Upon TFTP
> > download or something like this. So there should be no delay at all in
> > U-Boot related to this ethernet initialization when you don't use
> > ethernet.
>
> Right, that's how it should be in an ideal world.
>
> However, things are not that simple.
>
> First, the perception that this is how things should work has not been
> there forever. It has riped over time, and older boards / ports do
> things differently.
>
> Second, there are some CPUs / boards where "initializing" the ether-
> net just requires to whack a PY reset or simply take the PHT out of
> reset etc. Autonegotiation then takes place while U-Boot is doing
> other things, and by the time you want to use the Ethernet for a TFTP
> download or so it will be available with no or at least with greatly
> reduced delay.
Right. I know of such ports too and don't see any problems here since no delay
is imposed.
> But there are other implementations which wait for
> autonegotiation to complete.
I don't see a reason why a board should wait for autonegotionation to
complete, when the interface is not used. This should be fixed.
Best regards,
Stefan
=====================================================================
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80 Email: office at denx.de
=====================================================================
More information about the U-Boot
mailing list