FEC question about setting SIEL register

Dan Malek dan at netx4.com
Wed Aug 9 06:11:03 EST 2000

Graham Stoney wrote:

> ....  The culprit was that I hadn't
> configured the PHY MII link interrupt (which is on external IRQ5 on our board)
> as edge triggerred in the SIU Interrupt Edge/Level (SIEL) register.

Yeah....There are about a bazillion different pin multiplexing
combinations on these parts.  You really should have a very methodical
procedure to verify all of them, usually as part of the design process
before hardware CAD.

> Setting the SIEL is trivial enough, but where abouts is the right place to
> do it: in the fec.c driver, or in the 8xxrom/boot loader?

Normally I do all of this in a boot rom.  The I/O pin configuration
necessary to make even minimal forward progress must be done very early,
so I just do all of it there in one place.

> ......  The FADS code in
> fec.c doesn't set the SIEL,

Nope.  It never did.

> .... and it doesn't seem to be set in the FADS code in
> 8xxrom/fadsrom either, so I would conclude that it probably suffers the same
> problem.

It should be, but I screwed that up the first time.  The next logical
place (and where it used to exist), was in m8xx_setup.c in the
function m8xx_init_IRQ().  Since I don't have a FADS board any longer
for testing, and everyone else was connecting this interrupt to a
port C pin, the code just disappeared as part of the new interrupt

	-- Dan

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