Re: patch for SBS K2: don't initialise the L2 cache

Re: patch for SBS K2: don't initialise the L2 cache

[Matt Porter]

On Wed, Jun 20, 2001 at 07:01:01PM -0700, Michael Sokolov wrote:
> Hi there,
>
> Below is a patch to linuxppc_2_4_devel for the SBS K2 board. The current
> linuxppc_2_4_devel when booting on the K2 does its own L2 cache initialisation.
> This is no good. L2 cache initialisation should be left to the board firmware.
> The way the current linuxppc_2_4_devel sets up the L2 cache on the K2 works for
> a really ancient K2 we've had laying in the office since before the Flood (it
> was on that board that I reported success with linuxppc_2_4_devel earlier), but
> it blows up on all K2s of any recency (since April of last year I think). It
> certainly doesn't work on the K2s that are being shipped now (rev J), as SBS
> has changed (corrected) the L2 cache hardware on the new K2 revisions.

The only firmware available to date for an SBS K2 is PMON.  PMON does not
configure the L2 cache.  Older rev boards used a differential clock.  I've
finally received the new docs, so I'm updating the port to read the
single-ended/differential l2clk onboard register so it sets the L2CR
accordingly.  If docs were provided as they were updated with this new
feature, then the port would have been working.

When a firmware release is made available that properly sets up the L2CR
then I'll be happy to remove the L2CR setup code, not before.

--
Matt Porter
MontaVista Software, Inc.
mporter@mvista.com

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Re: patch for SBS K2: don't initialise the L2 cache

[Michael Sokolov]

Matt Porter <mporter@mvista.com> wrote:

> The only firmware available to date for an SBS K2 is PMON.  PMON does not
> configure the L2 cache.
>
> [...]
>
> When a firmware release is made available that properly sets up the L2CR
> then I'll be happy to remove the L2CR setup code, not before.

Here is the situation. I personally dislike PMON (quite strongly), and from my
personal conversations with Matt I've gathered that he shares my belief. (Matt,
please correct me if I'm wrong.) Furthermore, I'm ready to venture a guess that
any of the Linux/PPC maintainers who are Free Hackers (as opposed to
representing companies with a stake in the matter), given a demo and
description of PMON versus other possible firmware would very likely also find
PMON inferior. However, so far it seems like (for reasons that are outside my
realm of responsibility) SBS wants to stick with PMON for what it ships to
customers.

Here is what I propose to the Free Linux/PPC maintainers. Remember that the
very purpose of the Free public tree is to serve the interests of the Free
People not dominated by the interests of any particular company. Just like Red
Hat or anybody else working on GCC cannot make changes to the public GCC tree
only because their customers want the change and just like MontaVista or
anybody else working on Linux cannot make changes to the public Linux tree only
because their customers want the change, I similarly suggest that SBS's non-
technically-justifiable need to ship PMON to customers instead of StarMON be
kept out of the public Linux tree. I suggest that Free public Linux/PPC support
booting on SBS boards only under StarMON and not under PMON, even if SBS has to
ship PMON and an altered version of Linux that boots under it to its customers.
This way customers who insist on getting PMON can get it directly from SBS
without imposing it on the rest of the free world, and Free Hackers who want to
go by technical considerations only and not management decisions can use Free
StarMON and Free Linux from the net. If a board came with PMON, replacing it
with StarMON takes one erase/program cycle of the flash, of which the flash
manufacturer guarantees at least a million.

--
Michael Sokolov				5791 VAN ALLEN WAY
Software Engineer			CARLSBAD CA 92008-7321 USA
SBS Technologies, Inc.			Phone: +1-760-438-6900 x2347
Communications Products			    or +1-888-SBS-COMM x2347
					Fax:   +1-760-438-6904
					E-mail: msokolov@sbs.com
					     or msokolov@ivan.Harhan.ORG

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