Re: [PATCH] powerpc: Add Marvell mv64x60 udbg putc/getc functions

On Fri, Jun 08, 2007 at 12:15:15PM +1000, Michael Ellerman wrote:

On Wed, 2007-06-06 at 10:29 -0700, Dale Farnsworth wrote:

quoted

On Wed, Jun 06, 2007 at 04:06:05PM +1000, Paul Mackerras wrote:

quoted

Dale Farnsworth writes:

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Paul, this patch is unchanged from the one I posted 10 days ago.
At that time, I saw no discussion, other than Mark's ACK.  I'd 
argue that this is a bugfix, and hope that it could go into 2.6.22.

Um, it seems rather large, and in particular adds a fair bit of
completely new code.  Is there a simpler way of getting to an
acceptable point - e.g. just not use the udbg console on these boards?

Yeah, that was the first approach I took.  Unfortunately, currently the
udbg console is included unconditionally on arch/powerpc.  I created the
patch below to conditionalize the use of udbg console.  I thought it a
bit risky for 2.6.22, but I think it's the right approach long term.

quoted

If we don't have udbg support for them then the udbg console would
seem a bit pointless, no?

There is value in that with the udbg console we do see console output
much earlier.  While there's some new code (I didn't think it was all
that much), the impact is limited to the single platform now using the
mv64x60 console port, the prpmc2800.

You don't select PPC_UDBG for any of the cell platforms, which AFAICT
means you'll break early debugging on those.

Actually, I do select PPC_UDBG for PPC_IBM_CELL_BLADE (via
PPC_UDBG_16550) and for PPC_CELLEB (via PPC_UDBG_BEAT).  I couldn't
figure out which console PPC_PS3 uses, but that support is noted as
incomplete, so I didn't spend much time researching it.

Still, it's difficult to be sure I caught them all; that's why I
decided to defer the patch until the next merge window.

I think you should be able to do this in terms of
CONFIG_PPC_EARLY_DEBUG, which already exists.

Nope.  Many platforms use the udbg console early on without enabling
CONFIG_PPC_EARLY_DEBUG.

-Dale