Re: [RFC][PATCH] Way for platforms to alter built-in serial ports
From: Benjamin Herrenschmidt (benh_at_kernel.crashing.org)
Date: 10/02/04
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To: Bjorn Helgaas <bjorn.helgaas@hp.com> Date: Sat, 02 Oct 2004 16:45:50 +1000
On Sat, 2004-10-02 at 00:58, Bjorn Helgaas wrote:
> My main point is that I think the early init stuff (i.e.,
> serial8250_isa_init_ports()) should go away, so we don't have the
> dichotomy of having the compiled-in stuff handled differently than
> the run-time enumerated stuff.
Right. But that's a long term goal ;)
> It really doesn't matter for ia64, since we discover all the ports
> via either PCI enumeration or ACPI. We don't put anything in
> old_serial_port[] at all. For platforms that can't do that,
> there'd still have to be compiled-in tables, but the entries
> should be added using the standard register_serial() interface
> just like everything else.
I discover everything at boot time via Open Firmware, though on
ppc32, embedded platforms have gazillion different ways of getting
to them.
> > In the meantime, that patch would fix urgent problems for ppc now so
> > I'd appreciate if Russell would consider it for inclusion asap. This
> > is the kind of subject on which everybody comes up with a different
> > "better" way to do it and no code, and nothign ever gets implemented
> > and we end up with no progress...
>
> We've both posted working code that are at least baby steps toward
> a better solution, so I hope we can make some progress.
Yes. Well, I suppose having a 8250_ppc{64}.c where I do the discovery
a bit like it's done with ACPI would be ok for everything but serial
console... I can do an OF plaform device that gets probed a bit late
though, and that wouldn't help for embedded stuffs, but then, those
people can always still use the hard coded table for a while ... :)
That would mean though having the kernel serial console for early boot
be separate from the 8250 driver... like you proposed. That would work
too... I have to ponder this approach, indeed probably better than
my patch provided you get your early uart stuff upstream :)
Ben.
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- Previous message: Paul Jackson: "Re: [Lse-tech] [PATCH] cpusets - big numa cpu and memory placement"
- In reply to: Bjorn Helgaas: "Re: [RFC][PATCH] Way for platforms to alter built-in serial ports"
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